Polish "Restore R2DBC MySQL support with Spring Boot 3.1 or later"

See gh-1285

start-site/src/main/java/io/spring/start/site/extension/dependency/springdata/R2dbcBuildCustomizer.java

@@ -56,13 +56,13 @@ public class R2dbcBuildCustomizer implements BuildCustomizer<Build> {
 
 	private final boolean sqlServerIsUnmanaged;
 
-	private final boolean mysqlR2dbcNewDependency;
+	private final boolean mysqlR2dbcIsAsyncerDependency;
 
 	public R2dbcBuildCustomizer(Version platformVersion) {
 		this.borcaOrLater = SPRING_BOOT_2_7_0_OR_LATER.match(platformVersion);
 		this.mariaDbIsUnmanaged = SPRING_BOOT_3_0_0_OR_LATER.match(platformVersion);
 		this.sqlServerIsUnmanaged = SPRING_BOOT_3_0_0_OR_LATER.match(platformVersion);
-		this.mysqlR2dbcNewDependency = SPRING_BOOT_3_1_0_OR_LATER.match(platformVersion);
+		this.mysqlR2dbcIsAsyncerDependency = SPRING_BOOT_3_1_0_OR_LATER.match(platformVersion);
 	}
 
 	@Override
@@ -74,11 +74,13 @@ public void customize(Build build) {
 			addManagedDriver(build.dependencies(), "org.mariadb", "r2dbc-mariadb",
 					this.mariaDbIsUnmanaged ? "1.1.3" : null);
 		}
-		if (build.dependencies().has("mysql") && !this.borcaOrLater) {
-			addManagedDriver(build.dependencies(), "dev.miku", "r2dbc-mysql");
-		}
-		if (build.dependencies().has("mysql") && this.mysqlR2dbcNewDependency) {
-			addManagedDriver(build.dependencies(), "io.asyncer", "r2dbc-mysql");
+		if (build.dependencies().has("mysql")) {
+			if (!this.borcaOrLater) {
+				addManagedDriver(build.dependencies(), "dev.miku", "r2dbc-mysql");
+			}
+			else if (this.mysqlR2dbcIsAsyncerDependency) {
+				addManagedDriver(build.dependencies(), "io.asyncer", "r2dbc-mysql");
+			}
 		}
 		if (build.dependencies().has("postgresql")) {
 			String groupId = this.borcaOrLater ? "org.postgresql" : "io.r2dbc";