updated changelog for 2.28.3

Update CHANGELOG.md (stellar#5201)

better description of txsub issue in notes

clean up markdown on 2.28.0 release notes

Bump Core and soroban-rpc versions (stellar#5137)

Bump Core and soroban-rpc versions (stellar#5137)

updated changelog notes for 2.27.0-rc2 release

Update changelog for 2.27.0 release (stellar#5055)

Fix TestReingestDB and TestFillGaps

Re-point Soroban RPC to the final Docker image (stellar#5054)