chore: correct the variable name in roster.proto

[edward-swirldslabs]

Fixes #15463

This should be merged soon after: hashgraph/hedera-protobufs#416

[jsync-swirlds]

Don't forget to mirror these changes in hedera-protobufs.

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.00% (target: -1.00%)	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (4eb9c5b)	109026	67361	61.78%
Head commit (1979f81)	109026 (+0)	67358 (-3)	61.78% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#15465)	3	3	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 58.25%. Comparing base (4eb9c5b) to head (1979f81).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop   #15465   +/-   ##
==========================================
  Coverage      58.24%   58.25%           
- Complexity     21592    21598    +6     
==========================================
  Files           2779     2779           
  Lines         109209   109209           
  Branches       11177    11177           
==========================================
+ Hits           63609    63616    +7     
- Misses         41738    41741    +3     
+ Partials        3862     3852   -10     

Files with missing lines	Coverage Δ
...a/com/swirlds/platform/roster/RosterRetriever.java	91.78% <100.00%> (ø)
...a/com/swirlds/platform/roster/RosterValidator.java	94.44% <100.00%> (ø)
...rlds/platform/system/address/AddressBookUtils.java	69.31% <100.00%> (ø)

... and 16 files with indirect coverage changes