release-23.2: storage: disable metamorphism of excises and EFOS

[jbowens]

The new excise operation and eventually file-only snapshot (EFOS) features in Pebble are experimental. Within the 23.2 release, these features must only be enabled within the context of the disaggregated storage techncial preview. These features are still experimental and unstable.

Remove the metamorphism of these settings in tests in order to stabilize the 23.2 release branch. As we approach release, we want our test failures to be high signal, and failures dependent on these settings should not block the release. On the master branch these settings will be enabled unconditionally soon, and we'll get plenty of test coverage before their general availability in 24.1.

Epic: none
Informs #112221.
Informs #113973.
Informs #114056.
Release note: none
Release justification: non-production test-only changes

[blathers-crl]

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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 

[RaduBerinde]

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

[itsbilal]

LGTM as a safe change. I am pretty confident the bug only occurs when kv.snapshot_receiver.excise.enabled is enabled, and the EFOS setting isn't playing a role here, but until we have a root cause it might be safest to disable both to unblock the release.

[jbowens]

TFTRs!