Preserve common Go settings in go_stdlib_transition (#4637)

## Summary

Author: zbarsky-bot

Start `go_stdlib_transition` from all values in
`_reset_transition_keys`; the transition then only filters
`//go/config:tags` and disables `//go/private:bootstrap_nogo` and
`//command_line_option:collect_code_coverage`. This keeps each Go rule
and its `//:stdlib` dependency in the same configuration when resolving
the C++ toolchain.

Since #4599 removed `cgo_context_data`, each Go rule resolves the C++
toolchain directly. Resetting `//go/private:request_nogo` made ordinary
Go rules and `//:stdlib` resolve configuration-specific C++ runtime
archives in different configurations, so `GoLink` could reference an
archive that Bazel did not declare. Preserving every
`_reset_transition_keys` value prevents `//go/config:static`,
`//go/config:debug`, or future settings from recreating the same
mismatch.

The regression test verifies the two required `//:stdlib` configurations
for an ordinary Go target and `coverdata`. `//:stdlib` has no `_nogo`
attribute, so preserving `//go/private:request_nogo` does not run nogo
on `//:stdlib`.

## Testing

- `bazel test //tests/core/transition:hermeticity_test`
- `bazel test //tests:buildifier_test`