Add needed .gitignore files in back branches.

Tom Lane <tgl@sss.pgh.pa.us>

Commit: b1e58defb6a43fe35511eaa80858293b07c8b512
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: 2024-11-11T15:42:32Z
Releases: 12.21
Add needed .gitignore files in back branches.

v14 and earlier use generated test files, which require being
.gitignore'd to avoid git complaints when testing in-tree.

Security: CVE-2024-10979

Files