fix(bigtable): Fix mutate rows logic to handle errors

[aandreassa]

This PR combines fixes for 3 conformance tests. TestMutateRows_Retry_ExponentialBackoff, TestMutateRows_Retry_WithRoutingCookie and TestMutateRows_Retry_WithRetryInfo (b/405212985)

1. As mentioned in the bug: whenever mutate_rows fails, we want to push down the error status into each mutations.
2. RETRY_LIMIT logic seems to have an off-by-one error. When I run the tests as is, I get the error below:

mutaterows_test.go:335:
        	Error Trace:	/usr/local/<*>/.cache/toys/git/968ce209e7d6f7d24d68a25c9c8793c0/c65724cd1a35a8ace20e77cbb5b70323fe0ecd26/tests/mutaterows_test.go:335
        	Error:      	Not equal:
        	            	expected: 4
        	            	actual  : 3
        	Test:       	TestMutateRows_Retry_ExponentialBackoff
    mutaterows_test.go:346: Retry #1 delay: 1ms
    mutaterows_test.go:346: Retry #2 delay: 1ms
    mutaterows_test.go:348: Retry #3: Timeout waiting for retry (expecting 3 retries)
--- FAIL: TestMutateRows_Retry_ExponentialBackoff (0.51s)

3. Using a ‘cookie prefix’ for parsing metadata, like it is done in Java.

Tests are in googleapis/cloud-bigtable-clients-test.

[aandreassa]

@dazuma I had to merge known_failures.txt. PTAL again when you get a chance!

[dazuma]

Make sure the conventional commit tag gets fixed. This should at least be a fix:.