[configgrpc] fix integer overflow in grpc server configuration

[codeboten]

Change the value of max_recv_msg_size_mib from uint64 to int to avoid a case where misconfiguration caused an integer overflow. Added a Validate function to configgrpc as part of this to validate that users didn't set the value to something that would overflow when converted from megabytes to bytes.

[codeboten]

This bug was uncovered by the linter https://github.com/open-telemetry/opentelemetry-collector/actions/runs/10480357311/job/29027844869?pr=10935

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 91.88%. Comparing base (b10029c) to head (1334e0f).
Report is 27 commits behind head on main.

Files with missing lines	Patch %	Lines
config/configgrpc/configgrpc.go	90.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10948      +/-   ##
==========================================
- Coverage   91.89%   91.88%   -0.01%     
==========================================
  Files         411      411              
  Lines       19311    19319       +8     
==========================================
+ Hits        17745    17752       +7     
- Misses       1217     1218       +1     
  Partials      349      349              

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