Flaky Test: ProxyServerTest.testProbeConnection

The automated dependency reviewer bot detected a flaky test failure in PR #4539.

**Failed Test:** `ProxyServerTest.testProbeConnection`
**Failure Summary:** ProxyServerTest.testProbeConnection failed with expected:<0> but was:<1>
**Workflow Run:** https://github.com/GoogleCloudPlatform/pgadapter/actions/runs/27962456739

**Log Excerpt:**
```text
EP 2026-06-22T15:16:04.4094190Z [INFO] Running com.google.cloud.spanner.pgadapter.statements.SimpleParserTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4095370Z [INFO] Tests run: 19, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.008 s -- in com.google.cloud.spanner.pgadapter.statements.SimpleParserTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4096360Z [INFO] Running com.google.cloud.spanner.pgadapter.statements.PSQLTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4097480Z [INFO] Tests run: 29, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.057 s -- in com.google.cloud.spanner.pgadapter.statements.PSQLTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4098490Z [INFO] Running com.google.cloud.spanner.pgadapter.statements.TruncateStatementTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4099780Z [INFO] Tests run: 7, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 s -- in com.google.cloud.spanner.pgadapter.statements.TruncateStatementTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4100720Z [INFO] Running com.google.cloud.spanner.pgadapter.statements.PgCatalogTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4101760Z [INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0 s -- in com.google.cloud.spanner.pgadapter.statements.PgCatalogTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4102730Z [INFO] Running com.google.cloud.spanner.pgadapter.statements.SelectCurrentSettingStatementTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4796000Z [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.075 s -- in com.google.cloud.spanner.pgadapter.statements.SelectCurrentSettingStatementTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.4805050Z [INFO] Running com.google.cloud.spanner.pgadapter.OpenTelemetryMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.5643440Z [INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.078 s -- in com.google.cloud.spanner.pgadapter.OpenTelemetryMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:04.5645710Z [INFO] Running com.google.cloud.spanner.pgadapter.ServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:10.4854350Z [INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 5.915 s -- in com.google.cloud.spanner.pgadapter.ServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:10.4855360Z [INFO] Running com.google.cloud.spanner.pgadapter.SSLMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:10.8895060Z [INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.399 s -- in com.google.cloud.spanner.pgadapter.SSLMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:10.8897210Z [INFO] Running com.google.cloud.spanner.pgadapter.JdbcParametersMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:11.9714910Z [INFO] Tests run: 24, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.064 s -- in com.google.cloud.spanner.pgadapter.JdbcParametersMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:11.9819670Z [INFO] Running com.google.cloud.spanner.pgadapter.DomainSocketsTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:12.1371740Z [INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.168 s -- in com.google.cloud.spanner.pgadapter.DomainSocketsTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:12.1404380Z [INFO] Running com.google.cloud.spanner.pgadapter.JdbcSimpleModeMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:13.0618170Z [INFO] Tests run: 76, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.902 s -- in com.google.cloud.spanner.pgadapter.JdbcSimpleModeMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:16:13.0619170Z [INFO] Running com.google.cloud.spanner.pgadapter.csharp.NpgsqlMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.3996280Z [INFO] Tests run: 46, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 72.31 s -- in com.google.cloud.spanner.pgadapter.csharp.NpgsqlMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.4100760Z [INFO] Running com.google.cloud.spanner.pgadapter.EmulatedPgbenchMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.4826330Z [INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.083 s -- in com.google.cloud.spanner.pgadapter.EmulatedPgbenchMockServerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.4834480Z [INFO] Running com.google.cloud.spanner.pgadapter.ConnectionHandlerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.6855030Z [INFO] Tests run: 35, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.198 s -- in com.google.cloud.spanner.pgadapter.ConnectionHandlerTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.6856520Z [INFO] Running com.google.cloud.spanner.pgadapter.InvalidMessagesTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.8312080Z [INFO] Tests run: 10, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.139 s -- in com.google.cloud.spanner.pgadapter.InvalidMessagesTest
macos (8) UNKNOWN STEP 2026-06-22T15:17:25.8419150Z [INFO] Running com.google.cloud.spanner.pgadapter.ErrorHandlingTest
macos (8) UNKNOWN STEP
```

This issue was automatically created by the dependency reviewer bot.

Start with ProxyServerTest.testProbeConnection and reproduce the failure from workflow run 27962456739, checking the expected 0 versus actual 1 result. Trace the probe connection setup and identify the nondeterministic condition; done means the test reliably passes without masking the behavior.

Written by the indexing model from the issue text.