test: fix flaky tests

Fixes #3050
Fixes #3081
Fixes #3080

Author: olavloite

google-cloud-spanner/src/test/java/com/google/cloud/spanner/AsyncRunnerTest.java

@@ -261,12 +261,11 @@ public void asyncRunnerWaitsUntilAsyncUpdateHasFinished() throws Exception {
             executor);
     res.get();
     if (isMultiplexedSessionsEnabled()) {
+      // The mock server could have received a CreateSession request for a multiplexed session, but
+      // it could also be that that request has not yet reached the server.
       assertThat(mockSpanner.getRequestTypes())
-          .containsExactly(
-              CreateSessionRequest.class,
-              BatchCreateSessionsRequest.class,
-              ExecuteSqlRequest.class,
-              CommitRequest.class);
+          .containsAtLeast(
+              BatchCreateSessionsRequest.class, ExecuteSqlRequest.class, CommitRequest.class);
     } else {
       assertThat(mockSpanner.getRequestTypes())
           .containsExactly(

google-cloud-spanner/src/test/java/com/google/cloud/spanner/OpenTelemetrySpanTest.java

@@ -231,7 +231,7 @@ public void setUp() throws Exception {
             .setSessionPoolOption(
                 SessionPoolOptions.newBuilder()
                     .setMinSessions(2)
-                    .setWaitForMinSessions(Duration.ofSeconds(5))
+                    .setWaitForMinSessions(Duration.ofSeconds(10))
                     .build());
 
     spanner = builder.build().getService();

google-cloud-spanner/src/test/java/com/google/cloud/spanner/connection/ConnectionTest.java

@@ -290,7 +290,10 @@ public void testMaxSessions()
         assertThat(count1.isDone()).isTrue();
         assertThat(count2.isDone()).isTrue();
         if (isMultiplexedSessionsEnabled(connection1.getSpanner())) {
-          assertThat(mockSpanner.numSessionsCreated()).isEqualTo(2);
+          // We don't use the multiplexed session, so we don't know whether the server had time to
+          // create it or not. That means that we have between 1 and 2 sessions on the server.
+          assertThat(mockSpanner.numSessionsCreated()).isAtLeast(1);
+          assertThat(mockSpanner.numSessionsCreated()).isAtMost(2);
         } else {
           assertThat(mockSpanner.numSessionsCreated()).isEqualTo(1);
         }