Re-target Cosmos Linux emulator test skips at the specific upstream bugs

[Copilot]

A handful of Cosmos tests are skipped on the Linux emulator under a single umbrella reference to azure-cosmos-db-emulator-docker#292. After running the tests and isolating each failure with a stand-alone Microsoft.Azure.Cosmos repro, the failures map to three distinct emulator bugs (now filed individually) plus a residual set of EF-side issues that legitimately still belong under #292.

Changes

• Group 1 — ETag ignored under AllowBulkExecution (Update/CosmosBulkConcurrencyTest.cs, the two Updating_then_* overrides): retag #292 → #319.
• Group 2 — server-side scripts unsupported (CosmosTransactionalBatchTest.SaveChanges_transaction_behavior_always_succeeds_for_single_entity_with_trigger): tag with #294.
• Group 3 — multi-byte UTF-8 in id/PK returns 500 Postgres E22P05 (CosmosTransactionalBatchTest.SaveChanges_update_id_contains_special_chars_…): tag with #323.
• Split the class-level skip on CosmosTransactionalBatchTest into per-method [CosmosCondition(IsNotLinuxEmulator)] so each group carries its own URL. Tests in the class that still fail for unrelated EF-side reasons keep the original #292 comment; passing tests are no longer skipped.

// Before — one URL covering unrelated failure modes
[CosmosCondition(CosmosCondition.IsNotLinuxEmulator)]
public class CosmosTransactionalBatchTest(...) : ...

// After — each emulator bug tagged individually
[ConditionalFact]
// https://github.com/Azure/azure-cosmos-db-emulator-docker/issues/294
[CosmosCondition(CosmosCondition.IsNotLinuxEmulator)]
public virtual async Task SaveChanges_transaction_behavior_always_succeeds_for_single_entity_with_trigger() { ... }

[ConditionalTheory, InlineData(true), InlineData(false)]
// https://github.com/Azure/azure-cosmos-db-emulator-docker/issues/323
[CosmosCondition(CosmosCondition.IsNotLinuxEmulator)]
public virtual async Task SaveChanges_update_id_contains_special_chars_...(bool isIdSpecialChar) { ... }