fixup exec-env, follow symlinks in find

What does this MR do?

Switch the arguments to find in exec-env script to use -L instead of -P, so that symlinks are followed rather than ignored.

Related issues

gitlab-org/charts/gitlab#3254 (closed)

Checklist

See Definition of done.

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Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com

Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Integration tests added to GitLab QA
• The impact any change in container size has should be evaluated