Avoid collision in execution log postfix (#10205)

uname is the name for Linux and Linux_scala_2_12 which causes builds
to override each other and it looks like that might even break in case
of concurrent uploads although that could also be general flakiness in Azure.

changelog_begin
changelog_end

build.sh

@@ -14,7 +14,7 @@ ARTIFACT_DIRS="${BUILD_ARTIFACTSTAGINGDIRECTORY:-$PWD}"
 mkdir -p "${ARTIFACT_DIRS}/logs"
 
 tag_filter=""
-if [[ "$execution_log_postfix" == "_Darwin" ]]; then
+if [[ "$(uname)" == "Darwin" ]]; then
   tag_filter="-dont-run-on-darwin,-scaladoc,-pdfdocs"
 fi
 

ci/build-unix.yml

@@ -32,7 +32,7 @@ steps:
     displayName: 'Platform-agnostic lints and checks'
     condition: and(succeeded(), eq(variables['Agent.OS'], 'Linux'))
 
-  - bash: ./build.sh "_$(uname)"
+  - bash: ./build.sh "_${{parameters.name}}"
     displayName: 'Build'
     env:
       DAML_SDK_RELEASE_VERSION: ${{parameters.release_tag}}