sql: catch panics in virtual table generators

[yuzefovich]

This commit improves the stability of CRDB by introducing the panic-catcher into the goroutine that is spun up for generating the contents of the virtual tables. Previously, if the generator function ran into a panic, this would crash the server, and now instead only the query requiring the contents of the vtable will see an error.

Fixes: #135760.

Release note: None

[cockroach-teamcity]

This change is 

[yuzefovich]

TFTRs!

bors r+

[craig[bot]]

Build succeeded:

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

[blathers-crl[bot]]

Based on the specified backports for this PR, I applied new labels to the following linked issue(s). Please adjust the labels as needed to match the branches actually affected by the issue(s), including adding any known older branches.

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Issue #135760: branch-release-23.2, branch-release-24.1, branch-release-24.2.

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