refactor: update sql_cmd_test.cc

[Harshvardhantomar]

Removed the unnecessary "DECLARE" from the file.

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

• What is the current behavior? (You can also link to an open issue here)

• What is the new behavior (if this is a feature change)?

[codecov]

Codecov Report

Merging #2093 (e7d8486) into main (b455771) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #2093      +/-   ##
============================================
- Coverage     75.70%   75.68%   -0.02%     
  Complexity      347      347              
============================================
  Files           615      615              
  Lines        116901   116901              
  Branches       1015     1015              
============================================
- Hits          88499    88481      -18     
- Misses        28193    28211      +18     
  Partials        209      209              

Impacted Files	Coverage Δ
src/cmd/sql_cmd_test.cc	99.60% <ø> (ø)
src/rpc/rpc_client.h	85.13% <0.00%> (-4.06%)	⬇️
src/zk/dist_lock.cc	81.81% <0.00%> (-1.52%)	⬇️
src/sdk/db_sdk.cc	63.45% <0.00%> (-1.13%)	⬇️
src/client/tablet_client.cc	55.36% <0.00%> (-0.23%)	⬇️
src/tablet/tablet_impl.cc	60.14% <0.00%> (-0.15%)	⬇️
src/nameserver/name_server_impl.cc	42.80% <0.00%> (-0.02%)	⬇️

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[github-actions]

SDK Test Report

  75 files    75 suites   5m 38s ⏱️
163 tests 161 ✔️ 2 💤 0 ❌
204 runs  202 ✔️ 2 💤 0 ❌

Results for commit e7d8486.

[github-actions]

Linux Test Report

       54 files       196 suites   52m 0s ⏱️
  9 008 tests   9 004 ✔️ 4 💤 0 ❌
13 259 runs  13 255 ✔️ 4 💤 0 ❌

Results for commit e7d8486.

[tobegit3hub]

LGTM