[dotnet] Fix computing manifest version band. (#17536)

We need to use 'DOTNET_MANIFEST_VERSION_BAND' instead of
'DOTNET_VERSION_BAND', because the former always ends with '00' (which
manifest version bands are supposed), while the latter can have other numbers
(for instance 7.0.100 vs 7.0.101 - the former is a valid manifest version
band, the latter isn't).

Make.config

@@ -611,13 +611,13 @@ DOTNET_BCL_DIR:=$(abspath $(TOP)/packages/microsoft.netcore.app.ref/$(DOTNET_BCL
 # The sdk version band has the last two digits set to 0: https://github.com/dotnet/sdk/blob/22c4860dcb2cf6b123dd641cc4a87a50380759d5/src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/SdkDirectoryWorkloadManifestProvider.cs#L52-L53
 DOTNET_MANIFEST_VERSION_BAND=$(shell echo $(DOTNET_VERSION_BAND) | sed 's/..$$/00/')
 ifeq ($(DOTNET_VERSION_PRERELEASE_COMPONENT),)
-DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_VERSION_BAND)
+DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_MANIFEST_VERSION_BAND)
 else ifeq ($(word 1,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT))),-rtm)
-DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_VERSION_BAND)
+DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_MANIFEST_VERSION_BAND)
 else ifeq ($(word 1,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT))),-servicing)
 DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_MANIFEST_VERSION_BAND)
 else
-DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_VERSION_BAND)$(word 1,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT))).$(word 2,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT)))
+DOTNET_MANIFEST_VERSION_WITH_PRERELEASE_COMPONENT=$(DOTNET_MANIFEST_VERSION_BAND)$(word 1,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT))).$(word 2,$(subst ., ,$(DOTNET_VERSION_PRERELEASE_COMPONENT)))
 endif
 
 # We must do the same for our version band: the last two digits must be set to 0.