Revert "Upgrade to google.golang.org/grpc v1.66.2 / modify certain protobuf messages to retain their unmarshaling buffer"

[charleskorn]

Reverts #9401

Running go test -v -run="TestBothEnginesReturnSameResultsForBenchmarkQueries/a_100,.*" from pkg/streamingpromql/benchmarks fails roughly 50% of the time for me, and it looks like Prometheus' engine is getting corrupted label names and values, for example:

=== RUN   TestBothEnginesReturnSameResultsForBenchmarkQueries/2_*_a_100,_range_query_with_100_steps
    utils.go:61:
        	Error Trace:	/Users/charleskorn/Repositories/Grafana/mimir/pkg/streamingpromql/testutils/utils.go:61
        	            				/Users/charleskorn/Repositories/Grafana/mimir/pkg/streamingpromql/benchmarks/comparison_test.go:111
        	Error:      	Not equal:
        	            	expected: labels.Labels{labels.Label{Name:"\x03", Value:"\n"}}
        	            	actual  : labels.Labels{labels.Label{Name:"l", Value:"0"}}

        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -2,4 +2,4 @@
        	            	  (labels.Label) {
        	            	-  Name: (string) (len=1) "\x03",
        	            	-  Value: (string) (len=1) "\n"
        	            	+  Name: (string) (len=1) "l",
        	            	+  Value: (string) (len=1) "0"
        	            	  }
        	Test:       	TestBothEnginesReturnSameResultsForBenchmarkQueries/2_*_a_100,_range_query_with_100_steps

(the result from Prometheus' engine is the expected value in this test, MQE is the actual)

Another sample failure:

=== RUN   TestBothEnginesReturnSameResultsForBenchmarkQueries/a_100,_range_query_with_1000_steps
    utils.go:61:
        	Error Trace:	/Users/charleskorn/Repositories/Grafana/mimir/pkg/streamingpromql/testutils/utils.go:61
        	            				/Users/charleskorn/Repositories/Grafana/mimir/pkg/streamingpromql/benchmarks/comparison_test.go:111
        	Error:      	Not equal:
        	            	expected: labels.Labels{labels.Label{Name:"\x00(\x03@\n\x01\xd0\x02", Value:"\x00\xa0\xfd\x00("}, labels.Label{Name:"\xd0", Value:"4\x00"}}
        	            	actual  : labels.Labels{labels.Label{Name:"__name__", Value:"a_100"}, labels.Label{Name:"l", Value:"0"}}

        	            	Diff:
        	            	--- Expected
        	            	+++ Actual
        	            	@@ -2,8 +2,8 @@
        	            	  (labels.Label) {
        	            	-  Name: (string) (len=8) "\x00(\x03@\n\x01\xd0\x02",
        	            	-  Value: (string) (len=5) "\x00\xa0\xfd\x00("
        	            	+  Name: (string) (len=8) "__name__",
        	            	+  Value: (string) (len=5) "a_100"
        	            	  },
        	            	  (labels.Label) {
        	            	-  Name: (string) (len=1) "\xd0",
        	            	-  Value: (string) (len=2) "4\x00"
        	            	+  Name: (string) (len=1) "l",
        	            	+  Value: (string) (len=1) "0"
        	            	  }
        	Test:       	TestBothEnginesReturnSameResultsForBenchmarkQueries/a_100,_range_query_with_1000_steps

These tests consistently pass without the change in #9401.

[colega]

Reverted just the conflicting part: #9721