[stable13] Fix integer overflow in ChunkingPlugin

[MorrisJobke]

Avoids errors when the size exceeds MAX_INT because of the cast to int. Better cast it to float to avoid this.

Backport of #8112

[nickvergessen]

Same code as in master

[codecov]

Codecov Report

Merging #8752 into stable13 will decrease coverage by <.01%.
The diff coverage is 100%.

@@ Coverage Diff @@## stable13 #8752 +/- ##
==============================================
- Coverage 51.3% 51.29% -0.01% - Complexity 25017 25020 +3 
==============================================
Files 1609 1609 Lines 95285 95288 +3 Branches 1376 1376 ==============================================
Hits 48882 48882 - Misses 46403 46406 +3

Impacted Files	Coverage Δ	Complexity Δ
apps/dav/lib/Upload/ChunkingPlugin.php	96.29% <100%> (ø)	8 <0> (ø)	⬇️
lib/private/Template/JSCombiner.php	87.5% <0%> (-1.61%)	31% <0%> (+1%)
...b/private/Files/ObjectStore/ObjectStoreStorage.php	66.39% <0%> (-0.56%)	75% <0%> (+1%)
apps/dav/lib/Connector/Sabre/File.php	74.04% <0%> (+0.18%)	102% <0%> (+1%)	⬆️

[MorrisJobke]

Also 👍 from me, because I only did a straight cherry-pick