libpod: add missing return in WaitForConditionWithInterval()

AS pointed out by Valentin on #25491, it is not an actual bug but this
is makes it more clear how it works and should not confuse readers why
this case has no return.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

libpod/container_api.go

@@ -775,6 +775,7 @@ func (c *Container) WaitForConditionWithInterval(ctx context.Context, waitTimeou
 							exitCode, err := c.runtime.state.GetContainerExitCode(c.ID())
 							if err == nil {
 								trySend(exitCode, nil)
+								return
 							}
 
 							trySend(-1, nil)