fix(http): use user-provided ClientBootstrap in HttpConnection

[abhu85]

Summary

Fix condition that checked uninitialized options.bootstrap (always null after AWS_ZERO_STRUCT) instead of connectionOptions.Bootstrap. This caused user-provided ClientBootstrap to never be used.

Changes

• Changed line 136 in source/http/HttpConnection.cpp from checking options.bootstrap to connectionOptions.Bootstrap

Test plan

• Code review passed
• Build tests (requires CMake + submodules setup)

Fixes #819

[abhu85]

Friendly ping for review. This is a 1-line fix for #819 where the user-provided ClientBootstrap was being ignored due to checking the wrong variable (options.bootstrap which is always null after AWS_ZERO_STRUCT instead of connectionOptions.Bootstrap).