Simplify slashes queue processing

[nanocryk]

Simplified how slashes queue is constructed and processed, and trigger "page" processing once every block.

[github-actions]

WASM runtime size check:

Compared to target branch

dancebox runtime: 1416 KB (no changes) ✅

flashbox runtime: 824 KB (no changes) ✅

dancelight runtime: 2156 KB (no changes) ✅

container chain template simple runtime: 1124 KB (no changes) ✅

container chain template frontier runtime: 1400 KB (no changes) ✅

[github-actions]

Coverage Report

(master)

@@                              Coverage Diff                              @@
##           agustin-map-slashes   jeremy_slashes_on_initialize      +/-   ##
=============================================================================
+ Coverage                65.24%                         65.28%   +0.04%     
  Files                      329                            329              
- Lines                    57701                          57694       -7     
=============================================================================
+ Hits                     37646                          37664      +18     
- Misses                   20055                          20030      -25     

Files Changed	Coverage
/pallets/external-validator-slashes/src/lib.rs	78.10% (+3.39%)	✅
/pallets/external-validators-rewards/src/lib.rs	89.58% (+1.39%)	✅
/primitives/bridge/src/lib.rs	54.89% (-2.91%)	❗
/primitives/bridge/src/symbiotic_message_processor.rs	90.00% (-2.00%)	❗

Coverage generated Wed Jan 8 16:01:50 UTC 2025