chore: Deprecate GetAccountBalance query

[ibankov]

Deprecates the CryptoGetAccountBalance query. Marks the protobuf messages, RPC, and handler as deprecated with mirror-node migration guidance, and removes the query from genesis and test throttle definitions.

The test-client/yahcli switch from CryptoGetAccountBalance to CryptoGetInfo landed separately in #26740.

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[lfdt-bot]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@             Coverage Diff              @@
##               main   #26466      +/-   ##
============================================
+ Coverage     70.54%   70.56%   +0.01%     
- Complexity    11692    11693       +1     
============================================
  Files          2586     2586              
  Lines        108553   108553              
  Branches      12166    12165       -1     
============================================
+ Hits          76584    76605      +21     
+ Misses        27971    27954      -17     
+ Partials       3998     3994       -4     

Files with missing lines	Coverage Δ	Complexity Δ
...s/sysfiles/validation/ExpectedCustomThrottles.java	100.00% <ø> (ø)	2.00 <0.00> (ø)
.../impl/handlers/CryptoGetAccountBalanceHandler.java	89.87% <ø> (ø)	17.00 <0.00> (ø)

... and 12 files with indirect coverage changes

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[github-actions]

Node: HAPI Test (Atomic Batch) Results

  167 files  ±0      1 errors  166 suites   - 1   2h 32m 9s ⏱️ + 8m 1s
  293 tests  - 1    292 ✅  - 1  1 💤 ±0  0 ❌ ±0 
1 655 runs   - 1  1 654 ✅  - 1  1 💤 ±0  0 ❌ ±0 

For more details on these parsing errors, see this check.

Results for commit 30fad75. ± Comparison against base commit d3e580c.

This pull request removes 1 test.

com.hedera.services.bdd.suites.validation.ConcurrentSubprocessValidationTest ‑ as written

♻️ This comment has been updated with latest results.

[jsync-swirlds]

Proto changes look good.

Very happy to finally see this deprecated.

[testlens-app]

✅ All tests passed ✅

🏷️ Commit: e7291d3
▶️ Tests: 54831 executed
⚪️ Checks: 108/108 completed

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