Don't send message to Ethereum with zero rewards

[nanocryk]

• Early return if token inflation or points are zero.
• Refactor the code to favor if-guard style (if => early return, avoid nesting)
• Update tests that assumed message was always emitted

[github-actions]

WASM runtime size check:

Compared to target branch

dancebox runtime: 1416 KB (no changes) ✅

flashbox runtime: 824 KB (no changes) ✅

dancelight runtime: 2176 KB (no changes) ✅

container chain template simple runtime: 1116 KB (no changes) ✅

container chain template frontier runtime: 1404 KB (no changes) ✅

[github-actions]

Coverage Report

(master)

@@                              Coverage Diff                              @@
##           master   jeremy-dont-send-message-for-zero-rewards      +/-   ##
=============================================================================
+ Coverage   66.04%                                      66.10%   +0.06%     
  Files         335                                         335              
+ Lines       58850                                       58933      +83     
=============================================================================
+ Hits        38866                                       38957      +91     
- Misses      19984                                       19976       -8     

Files Changed	Coverage
/chains/orchestrator-relays/runtime/dancelight/src/genesis_config_presets.rs	60.09% (+0.06%)	✅
/chains/orchestrator-relays/runtime/dancelight/src/lib.rs	69.06% (+0.45%)	✅
/chains/orchestrator-relays/runtime/dancelight/src/tests/common/mod.rs	97.55% (+0.18%)	✅
/chains/orchestrator-relays/runtime/dancelight/src/tests/slashes.rs	98.63% (+0.05%)	✅
/pallets/external-validators/src/lib.rs	91.03% (+0.18%)	✅
/pallets/external-validators-rewards/src/lib.rs	88.54% (+0.68%)	✅

Coverage generated Fri Feb 7 14:33:01 UTC 2025