Remove unused variables in OfflineStorage_Room.cpp and HttpClient_Android.cpp

[ankitkapur]

Remove unused variables in these CPP files that cause build breaks on various compilers.
See OTELCPP for Details.

[ankitkapur]

auto result_count = env->GetArrayLength(java_records);
change to size_t

[ankitkapur]

remove
static constexpr char newRecordSignature[] =
"(JIIJIJ[B)Lcom/microsoft/applications/events/StorageRecord;";

[ankitkapur]

remove
int persist_lb = static_cast(EventPersistence_Normal);
int persist_ub = static_cast(EventPersistence_DoNotStoreOnDisk);

[ankitkapur]

remove
size_t index = 0;

[bmehta001]

Hi @ankitkapur, Thanks for creating this issue. It will be closed by #1466.