Disable the default workingDir and HOME overrides

[ghost]

Changes

See #3878 for a previous attempt at merging this that has gotten stuck.

Prior to this commit Steps were given a default HOME env var of "/tekton/home" and a default workingDir of "/workspace". These defaults collide with any value set by the Step's image Dockerfile.

This commit removes the default home and workingDir overrides (except in those few cases where they're still expected, like PipelineResources).

See https://groups.google.com/g/tekton-dev/c/C-PL8VYN51E/m/el5Fca_PDAAJ for our tekton-dev announcement of this change.

See #1836 for the original problem description and workingDir tracking issue.

See #2013 for the HOME change tracking issue.

See https://github.com/tektoncd/pipeline/blob/main/docs/deprecations.md for our documented dates for these deprecations.

See https://github.com/tektoncd/pipeline/blob/main/api_compatibility_policy.md#alpha-beta-and-ga
for our beta deprecation policy.

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Docs included if any changes are user facing
• Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including
  functionality, content, code)
• Release notes block below has been filled in or deleted (only if no user facing changes)

Release Notes

Steps no longer receive a default HOME env var of "/tekton/home", nor a default workingDir of "/workspace". 

action required: if you rely on these defaults you now have a choice to make: either update your Task steps to include the workingDir and HOME env or set the "disable-home-env-overwrite" and "disable-working-directory-overwrite" feature flags to "false". We plan to continue supporting these flags for another 9 months following the release of 0.24 and then they too will be removed.

[tekton-robot]

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[ghost]

/kind misc

[ghost]

Ohhhh kay. I get it now. This pr's commit was being rebased on top of the main branch before being tested, which does introduce another implicitEnvVars reference. oy. Rebasing on top of main exposes the problem.

[ghost]

Closing as dupe of #3878

[tekton-robot]

The following is the coverage report on the affected files.
Say /test pull-tekton-pipeline-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/pod/pod.go	87.4%	86.6%	-0.8

[tekton-robot]

@sbwsg: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-tekton-pipeline-build-tests	4bd1fa0	link	/test pull-tekton-pipeline-build-tests
pull-tekton-pipeline-integration-tests	4bd1fa0	link	/test pull-tekton-pipeline-integration-tests

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.

[tekton-robot]

@sbwsg: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-tekton-pipeline-build-tests	4bd1fa0	link	/test pull-tekton-pipeline-build-tests
pull-tekton-pipeline-integration-tests	4bd1fa0	link	/test pull-tekton-pipeline-integration-tests

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.