Make applicablee code changes to build a separate E2E binary for each provider, write buildspecs for separate provider

This issue deals with the build changes required to generate a separate binary for each provider, using build tags that will filter out all other tests except the ones for that provider. Some other changes include writing buildspecs for the providers, which just involves breaking down the current monolithic buildspec into more minimal ones.

Start by reviewing the current monolithic buildspec and the E2E test build-tag setup. Identify the provider-specific test groups and the build changes needed to produce one binary and buildspec per provider; done means each provider can be built separately while excluding other providers' tests.

Written by the indexing model from the issue text.