Delete long-obsolete tests and benchmarks

[tgoyne]

unit-tests-ios benchmark-common-tasks-ios: used by the pre-cmake build system.

benchmark-row-accessor: never updated for core 6 and the thing it was benchmarking isn't applicable any more.

benchmark-history-types: used to verify that moving the transaction logs into the Realm file wouldn't cause performance problems. The code being benchmarked no longer exists.

notifications-fuzzer: this was an important part of originally writing the diffing logic for notifications, but everything it exposed was turned into normal tests. It was never updated for core 6 and no bugs have ever been reported in the code this was testing.

test_client_reset_query_based.cpp: query-based sync is no longer a thing.

test_optional.cpp: this was actually testing std::optional. There's still some code in optional.hpp, but none of it was being tested here.

benchmark-transaction benchmark-prealloc benchmark-index benchmark-insert-add performance: these were pre-Realm benchmarks against the old macro-based TightDB API, which was deleted in 2016.

simple-connection: this was a manual testing tool from when sync first adopted websockets.

protocol_compact: this was a tool for testing one version of the server against a different version of the client, which we no longer care about.

There's a few other things in the test directory that don't currently build (benchmark-util-network and some of the fuzzers) but have been touched in the last few years and aren't testing something irrelevant so I left them.

[coveralls-official]

Pull Request Test Coverage Report for Build thomas.goyne_327

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 73 unchanged lines in 18 files lost coverage.
• Overall coverage decreased (-0.004%) to 90.822%

---

Files with Coverage Reduction	New Missed Lines	%
src/realm/index_string.cpp	1	85.17%
src/realm/index_string.hpp	1	93.48%
src/realm/query_expression.hpp	1	93.81%
src/realm/sync/noinst/server/server_history.cpp	1	63.7%
src/realm/util/file.cpp	1	78.73%
src/realm/uuid.cpp	1	98.48%
src/realm/table_view.cpp	2	92.99%
src/realm/sync/noinst/protocol_codec.hpp	3	74.03%
src/realm/table.cpp	3	90.14%
test/test_util_network.cpp	3	95.44%

Totals
Change from base Build 2310:	-0.004%
Covered Lines:	214449
Relevant Lines:	236121

---

💛 - Coveralls

[michael-wb]

LGTM