Don't emit nodes when calling .asBool on a Bool (backport #3637)

[mergify]

This is an automatic backport of pull request #3637 done by Mergify.
Cherry-pick of d5e65a3 has failed:

On branch mergify/bp/3.6.x/pr-3637
Your branch is up to date with 'origin/3.6.x'.

You are currently cherry-picking commit d5e65a337.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   src/test/scala/chiselTests/UIntOps.scala

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   core/src/main/scala/chisel3/Bits.scala
	deleted by us:   src/test/scala/chiselTests/LTLSpec.scala
	both modified:   src/test/scala/chiselTests/VerificationSpec.scala

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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Original PR Body

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• Backend code generation

Desired Merge Strategy

• Squash

Release Notes

This results in a slight improvement to emitted FIRRTL quality

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.5.x, 3.6.x, or 5.x depending on impact, API modification or big change: 6.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash), clean up the commit message, and label with Please Merge.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.