gateway-gcs: testRemoveMultipleObjects functional test fails (gcs server problem)

[ebozduman]

When minio-go functional test testRemoveMultipleObjects is run against gateway-gcs, it creates 1100 files, each 8 bytes in size, and then tries to remove them. However, gcs server cannot handle the load and fails with We encountered an internal error, please try again. error message.

We just simply don't need to push the gcs server to its edge in a test scenario like this, but instead use much smaller number of files to test multiple object removal functionality.