release-23.2: kv,admission: add missing admission headers

[blathers-crl]

Backport 1/1 commits from #116286 on behalf of @aadityasondhi.

/cc @cockroachdb/release

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This patch adds missing admission headers in a couple of places: txn_interceptor_heartbeater and replica_range_lease. Batch requests coming from these code paths are expected to bypass AC. Empty admission headers were accomplishing the same goal but this makes it more clear at what the intention is.

Informs #112680

Release note: None

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Release justification:

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

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  issues or test-only changes.
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[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is 

[sumeerbhola]

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @aadityasondhi)

[aadityasondhi]

TFTR!

Reviewable status: complete! 1 of 0 LGTMs obtained