Tags: fix for null tags in config

[johnsonaj]

Description

null values can be used as placeholders for tags that are not configured. These values should be ignored when resolving tag differences.

Relations

Closes #31583
Closes #31586

References

Output from Acceptance Testing

make testacc TESTARGS='-run=TestAccVPC_ -short' PKG=vpc

==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 20  -run=TestAccVPC_ -short -timeout 180m
    vpc_test.go:969: skipping long-running test in short mode
--- SKIP: TestAccVPC_IPAMIPv4BasicNetmask (0.00s)
    vpc_test.go:996: skipping long-running test in short mode
--- SKIP: TestAccVPC_IPAMIPv4BasicExplicitCIDR (0.00s)
    vpc_test.go:1024: skipping long-running test in short mode
--- SKIP: TestAccVPC_IPAMIPv6 (0.00s)
=== NAME  TestAccVPC_assignGeneratedIPv6CIDRBlockWithNetworkBorderGroup
    ec2_availability_zone_data_source_test.go:219: skipping since no Local Zones are available
--- SKIP: TestAccVPC_assignGeneratedIPv6CIDRBlockWithNetworkBorderGroup (0.85s)
--- PASS: TestAccVPC_DefaultTagsProviderAndResource_duplicateTag (31.26s)
--- PASS: TestAccVPC_tags_null (33.71s)
--- PASS: TestAccVPC_tags_computed (36.52s)
--- PASS: TestAccVPC_basic (41.38s)
--- PASS: TestAccVPC_bothDNSOptionsSet (51.27s)
--- PASS: TestAccVPC_enableNetworkAddressUsageMetrics (52.15s)
--- PASS: TestAccVPC_disabledDNSSupport (52.64s)
--- PASS: TestAccVPC_DefaultTags_updateToResourceOnly (57.54s)
--- PASS: TestAccVPC_disappears (23.38s)
--- PASS: TestAccVPC_DefaultTags_updateToProviderOnly (59.32s)
--- PASS: TestAccVPC_DynamicResourceTags_ignoreChanges (60.86s)
--- PASS: TestAccVPC_DynamicResourceTagsMergedWithLocals_ignoreChanges (61.29s)
--- PASS: TestAccVPC_defaultAndIgnoreTags (61.61s)
--- PASS: TestAccVPC_ignoreTags (62.98s)
--- PASS: TestAccVPC_updateDNSHostnames (63.97s)
--- PASS: TestAccVPC_DefaultTags_zeroValue (66.80s)
--- PASS: TestAccVPC_DefaultTagsProviderAndResource_nonOverlappingTag (70.15s)
--- PASS: TestAccVPC_DefaultTags_providerOnlyTestAccVPC_DefaultTags_providerOnly (70.23s)
--- PASS: TestAccVPC_DefaultTagsProviderAndResource_overlappingTag (70.82s)
--- PASS: TestAccVPC_tenancy (74.72s)
--- PASS: TestAccVPC_tags (56.09s)
--- PASS: TestAccVPC_assignGeneratedIPv6CIDRBlock (97.65s)
PASS
ok  	github.com/hashicorp/terraform-provider-aws/internal/service/ec2	100.941s

[github-actions]

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[jar-b]

LGTM 🚀

$ make testacc TESTARGS='-run=TestAccVPC_ -short' PKG=vpc
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/ec2/... -v -count 1 -parallel 20  -run=TestAccVPC_ -short -timeout 180m

--- PASS: TestAccVPC_DefaultTagsProviderAndResource_duplicateTag (27.56s)
=== CONT  TestAccVPC_DefaultTags_zeroValue
--- PASS: TestAccVPC_tags_computed (35.27s)
=== CONT  TestAccVPC_disappears
--- PASS: TestAccVPC_basic (40.40s)
=== CONT  TestAccVPC_tags_null
--- PASS: TestAccVPC_enableNetworkAddressUsageMetrics (52.74s)
--- PASS: TestAccVPC_disabledDNSSupport (52.98s)
--- PASS: TestAccVPC_bothDNSOptionsSet (54.31s)
--- PASS: TestAccVPC_DefaultTags_updateToResourceOnly (57.37s)
--- PASS: TestAccVPC_disappears (24.73s)
--- PASS: TestAccVPC_DefaultTags_updateToProviderOnly (60.03s)
--- PASS: TestAccVPC_DynamicResourceTagsMergedWithLocals_ignoreChanges (61.45s)
--- PASS: TestAccVPC_DynamicResourceTags_ignoreChanges (61.71s)
--- PASS: TestAccVPC_ignoreTags (64.08s)
--- PASS: TestAccVPC_defaultAndIgnoreTags (64.97s)
--- PASS: TestAccVPC_updateDNSHostnames (66.40s)
--- PASS: TestAccVPC_tags_null (27.19s)
--- PASS: TestAccVPC_DefaultTagsProviderAndResource_nonOverlappingTag (69.71s)
--- PASS: TestAccVPC_DefaultTagsProviderAndResource_overlappingTag (71.26s)
--- PASS: TestAccVPC_DefaultTags_providerOnlyTestAccVPC_DefaultTags_providerOnly (71.39s)
--- PASS: TestAccVPC_tags (76.47s)
--- PASS: TestAccVPC_tenancy (77.66s)
--- PASS: TestAccVPC_DefaultTags_zeroValue (52.34s)
--- PASS: TestAccVPC_assignGeneratedIPv6CIDRBlockWithNetworkBorderGroup (92.09s)
--- PASS: TestAccVPC_assignGeneratedIPv6CIDRBlock (101.82s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/ec2        105.123s

[github-actions]

This functionality has been released in v5.0.1 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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