Ignore validate generated files

[philderbeast]

After running sh validate.sh locally[^1], there are untracked files;

$ git status --untracked
On branch test/release-dry-run-9601
Your branch is up to date with 'origin/test/release-dry-run-9601'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	testdb/intree/cabal.project-test
	testdb/intree/store/ghc-8.8.4/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce/bin/alex
	testdb/intree/store/ghc-8.8.4/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce/cabal-hash.txt
	testdb/intree/store/ghc-8.8.4/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce/share/AlexTemplate.hs
	testdb/intree/store/ghc-8.8.4/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce/share/AlexWrappers.hs
	testdb/intree/store/ghc-8.8.4/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce/share/doc/LICENSE
	testdb/intree/store/ghc-8.8.4/incoming/alex-3.5.0.0-e-alex-41f8a1132e25d0a231e7f9fc4451befbbf41a4ba94929224d450e60261712fce.lock
	testdb/intree/store/ghc-8.8.4/package.db/package.cache
	testdb/intree/store/ghc-8.8.4/package.db/package.cache.lock

We can .gitignore these can't we?

[^1]: I ran validate on another branch but expect it would be the same on the master branch.

[ffaf1]

Should those be cleared rather than ignored?

[philderbeast]

@mpickering the intree stuff was added in #9671 wasn't it?

[mpickering]

I don't know if you want to clean them or ignore them. If you are running ./validate.sh multiple times then it will save you a lot of time if you just add them to ignore rather than clean.