Data corruption when appending to a blob.

Seems like the content we are getting is not the same as the one we have written to Azure backend:

=== RUN   TestAzureDriverSuite/TestConcurrentFileStreams
    testsuites.go:2160: 
        	Error Trace:	/builds/gitlab-org/container-registry/registry/storage/driver/testsuites/testsuites.go:2160
        	            				/builds/gitlab-org/container-registry/registry/storage/driver/testsuites/testsuites.go:1312
        	            				/usr/local/go/src/runtime/asm_amd64.s:1695
        	Error:      	Not equal: 

• https://gitlab.com/gitlab-org/container-registry/-/jobs/8829094542
• https://gitlab.com/gitlab-org/container-registry/-/jobs/8821402430
• https://gitlab.com/gitlab-org/container-registry/-/jobs/8821402471
• https://gitlab.com/gitlab-org/container-registry/-/jobs/8821402448