kvserver: enable skip of merge/consistency queue on external bytes

[dt]

trafficstars

Release note: none. Epic: none.

[blathers-crl[bot]]

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?

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

[cockroach-teamcity]

This change is 

[dt]

TFTR!

bors r+

[craig[bot]]

Build failed:

• local_roachtest

[dt]

bors r+

[craig[bot]]

Build failed:

• unit_tests

[dt]

bors r+

[craig[bot]]

Build succeeded:

• acceptance
• macos_arm64_build
• check_generated_code
• macos_amd64_build
• lint
• windows_build
• examples_orms
• linux_arm64_build
• linux_amd64_build
• local_roachtest
• local_roachtest_fips
• linux_amd64_fips_build
• docker_image_amd64
• unit_tests