Prevent Zend_Date from checking locale for know date codes

[MarcinNowakWebdeveloper]

Add U, X and c, as we know the codes are not real locales.

[joshua-bn]

With this many, I would use in_array() or isset() so it's more readable. But, looks good.

[fballiano]

can we know a little bit more about this?

[tmotyl]

@fballiano sure, this change is a performance optimization that we run on prod since more than a year.
Without it, Zend_Date tries to detect Locale for a given date even though the date is not locale aware.
The logic of fetching Locale is expensive at its requires a cache lookup.
So basically this change prevents multiple calls to Zend cache during request. Its especially painful/visible on requests with many date formatting e.g. reports.

[fballiano]

Thanks @tmotyl!
How did you find these "UXc" parts that you've added? Also, where there specific reasons to move from "!=" to "!=="?

[tmotyl]

@fballiano
See constants in https://github.com/OpenMage/magento-lts/blob/1.9.4.x/app/code/core/Zend/Date.php#L94-L94 and then look for their usage in the code.
And also
https://github.com/OpenMage/magento-lts/blob/1.9.4.x/app/code/core/Zend/Date.php#L800-L800

I have found the issue when investigating (profiling with blackfire) why some magento reports are taking ages to load / timeout.

Also, where there specific reasons to move from "!=" to "!=="?

Its a best practice, as both sides are strings, it doesn't make sense to have "!="

[github-actions]

Unit Test Results

1 files  ±0  1 suites  ±0   0s ⏱️ ±0s
0 tests ±0  0 ✔️ ±0  0 💤 ±0  0 ❌ ±0 
7 runs  ±0  5 ✔️ ±0  2 💤 ±0  0 ❌ ±0 

Results for commit bcb8390. ± Comparison against base commit 8e9ac45.