RUM-2467: Fix ConcurrentModificationException during ConsentAwareStorage.dropAll call

[0xnm]

What does this PR do?

We were removing items from collection during its traversal, this PR fixes that.

The issue doesn't reproduce with only single item in the collection, because modification check it done on the next iteration, so I also updated test to have multiple locked batches.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[mariusc83]

good catch

[codecov-commenter]

Codecov Report

Merging #1764 (c4595d6) into develop (b628685) will increase coverage by 0.05%.
Report is 2 commits behind head on develop.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1764      +/-   ##
===========================================
+ Coverage    83.43%   83.48%   +0.05%     
===========================================
  Files          469      469              
  Lines        16394    16391       -3     
  Branches      2448     2447       -1     
===========================================
+ Hits         13678    13683       +5     
+ Misses        2048     2039       -9     
- Partials       668      669       +1     

Files	Coverage Δ
...d/core/internal/persistence/ConsentAwareStorage.kt	98.78% <100.00%> (ø)

... and 23 files with indirect coverage changes