fix(bigtable)!: pass app profile id to connection as options

[dbolduc]

Fixes #9349

This tedious PR does two things:

1. stores the app profile in Table::options_ instead of Table::app_profile_id_. (Note that options_ is already passed in an OptionsSpan for each RPC). Legacy uses of app_profile_id_ become app_profile_id().
2. drops std::string const& app_profile_id from the Connection methods. We set upOptionsSpans in the Connection unit tests so we can verify that all RPCs set a request's app_profile_id field.

While this is a breaking change at HEAD, the methods are less than 2 weeks old and have not been included in a release yet. The upside of this change is that the method signature of the Connection is closer to that of the Table. And it's nice to have one less field to type.

My apologies for not validating the Table API surface before writing all the connection code.

Also, I decided not to perpetuate the if-call-options-use-call-options-else-use-conn-options logic. As @devbww pointed out earlier, the connection options are set once. They are merged into the client options. The client options are merged into the call options. So it must be the case that either the call options have a given option, or that neither the call options nor the connection options have a given option. Therefore, we should just use the call options.

---

This change is 

[google-cloud-cpp-bot]

Google Cloud Build Logs
For commit: 5c74a490e813d1db0bf1c6f424793aaebb989266

• Public Access Build Logs
• Cloud Build Console (requires auth)
• Kokoro Logs (requires auth)

ℹ️ NOTE: Kokoro logs are linked from "Details" below.

[codecov]

Codecov Report

Merging #9388 (5c74a49) into main (8b167c8) will decrease coverage by 0.00%.
The diff coverage is 99.49%.

@@            Coverage Diff             @@
##             main    #9388      +/-   ##
==========================================
- Coverage   94.67%   94.67%   -0.01%     
==========================================
  Files        1480     1480              
  Lines      135467   135506      +39     
==========================================
+ Hits       128251   128287      +36     
- Misses       7216     7219       +3     

Impacted Files	Coverage Δ
google/cloud/bigtable/data_connection.cc	16.98% <0.00%> (ø)
google/cloud/bigtable/data_connection.h	100.00% <ø> (ø)
google/cloud/bigtable/mocks/mock_data_connection.h	100.00% <ø> (ø)
...le/cloud/bigtable/internal/data_connection_impl.cc	99.15% <100.00%> (+0.01%)	⬆️
...gle/cloud/bigtable/internal/data_connection_impl.h	100.00% <100.00%> (ø)
...oud/bigtable/internal/data_connection_impl_test.cc	97.02% <100.00%> (+0.12%)	⬆️
google/cloud/bigtable/table.cc	99.35% <100.00%> (-0.01%)	⬇️
google/cloud/bigtable/table.h	98.51% <100.00%> (-0.71%)	⬇️
google/cloud/bigtable/table_test.cc	100.00% <100.00%> (ø)
...loud/bigtable/internal/connection_refresh_state.cc	97.22% <0.00%> (-2.78%)	⬇️
... and 4 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8b167c8...5c74a49. Read the comment docs.