Use normal severity for Phan checks

[MorrisJobke]

Extracted from #8375

[codecov]

Codecov Report

Merging #9314 into master will decrease coverage by 45.18%.
The diff coverage is n/a.

@@ Coverage Diff @@## master #9314 +/- ##
============================================
- Coverage 51.93% 6.74% -45.19% 
Complexity 25388 25388 ============================================
Files 1608 1608 Lines 95440 95440 Branches 1394 1394 ============================================
- Hits 49563 6437 -43126 - Misses 45877 89003 +43126

Impacted Files	Coverage Δ	Complexity Δ
apps/comments/lib/JSSettingsHelper.php	0% <0%> (-100%)	2% <0%> (ø)
lib/private/Security/CSRF/CsrfToken.php	0% <0%> (-100%)	5% <0%> (ø)
apps/files/lib/Activity/Settings/FileChanged.php	0% <0%> (-100%)	8% <0%> (ø)
...curity/Exceptions/StrictCookieMissingException.php	0% <0%> (-100%)	1% <0%> (ø)
apps/user_ldap/lib/Mapping/UserMapping.php	0% <0%> (-100%)	1% <0%> (ø)
apps/user_ldap/lib/Migration/UUIDFixGroup.php	0% <0%> (-100%)	1% <0%> (ø)
apps/files/appinfo/app.php	0% <0%> (-100%)	0% <0%> (ø)
apps/encryption/lib/Users/Setup.php	0% <0%> (-100%)	6% <0%> (ø)
...yBuilder/FunctionBuilder/SqliteFunctionBuilder.php	0% <0%> (-100%)	1% <0%> (ø)
lib/private/Hooks/LegacyEmitter.php	0% <0%> (-100%)	1% <0%> (ø)
... and 866 more

[MorrisJobke]

Okay this causes ~1200 warnings -> let's do this later