fix: improve directory fallback on Linux and trim local time identifier

[algebraic-dev]

This PR fixes:

• Problems in other linux distributions that the default tzdata directory is not the same as previously defined by ensuring it with a fallback behavior when directory is missing.
• Trim unnecessary characters from local time identifier.

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 0eca3bd55de7f29320e90b83ef2f43e9dff7546b --onto 20acc72a29a8bb4d55223651caa0553ffa82ac88. (2024-11-26 03:26:25)
• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase 0eca3bd55de7f29320e90b83ef2f43e9dff7546b --onto 9a17919ef11c2dba824498229633b8333a0b53d9. (2024-11-26 13:13:04)