Bump mongo from 5.0.20 to 5.0.21 in /test/IntegrationTests/docker (#2… #7234

Job	Run time
build / build (windows-2022, /c/ProgramData/OpenTelemetry .NET AutoInstrumentation/logs)	13m 13s
build / build (ubuntu-20.04, /var/log/opentelemetry/dotnet)	5m 9s
build / build (macos-11, /var/log/opentelemetry/dotnet)	10m 50s
build-container / build-container (alpine, linux-musl)	7m 24s
build-container / build-container (centos, linux-glibc)	6m 47s
test-build-container (alpine, alpine, linux-musl)	14m 55s
test-build-container (centos, centos, linux-glibc)	15m 3s
test-build-container (debian, centos, linux-glibc)	15m 26s
test-build-managed (net7.0, windows-2022)	19m 3s
test-build-managed (net7.0, ubuntu-20.04)	11m 29s
test-build-windows-container-tests (windows-2022, windows-only)	19m 47s
test-build-managed (net7.0, macos-11)	13m 46s
test-build-managed (net6.0, windows-2022)	14m 10s
test-build-native (windows-2022)	7m 50s
test-build-managed (net6.0, ubuntu-20.04)	13m 42s
test-build-managed (net6.0, macos-11)	13m 35s
test-build-managed (net462, windows-2022)	14m 47s
build-nuget-packages / build-nuget-packages	7m 1s
test-nuget-packages (ubuntu-20.04)	2m 38s
test-nuget-packages (macos-11)	5m 51s
test-nuget-packages (windows-2022)	10m 24s
	4h 2m 50s

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