Remove interpolation-only warning

[pselle]

These interpolations are removed when upgrading using 0.12upgrade, and are removed in terraform fmt in many cases.

I checked to see if some cases aren't currently fixed by fmt and it appears cases like ["${var.foo}"] aren't fixed by fmt, but others are. I think this is acceptable/follow-on work to fmt can be done if wanted.

[codecov]

Codecov Report

Merging #27835 (fa7c3d7) into master (28d3505) will decrease coverage by 0.06%.
The diff coverage is n/a.

Impacted Files	Coverage Δ
command/format/diagnostic.go	69.42% <ø> (ø)
configs/compat_shim.go	90.24% <ø> (-5.06%)	⬇️
configs/module_call.go	68.49% <ø> (-0.85%)	⬇️
configs/named_values.go	67.35% <ø> (-0.54%)	⬇️
configs/provider.go	82.52% <ø> (-0.34%)	⬇️
configs/resource.go	80.95% <ø> (-0.30%)	⬇️
internal/getproviders/didyoumean.go	54.32% <ø> (ø)
internal/getproviders/filesystem_search.go	63.20% <ø> (ø)
internal/legacy/terraform/resource_address.go	62.31% <ø> (ø)
provider_source.go	24.73% <ø> (ø)
... and 5 more

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.