Update AMI_USERS parsing

Author: petetomasik

Makefile

@@ -25,7 +25,7 @@ AMI_PUBLIC ?= false
 AMI_USERS ?=
 
 # Convert comma-separated AMI_USERS to JSON array format
-AMI_USERS_JSON = $(if $(AMI_USERS),[$(shell echo '$(AMI_USERS)' | $(SED) 's/[^,][^,]*/"&"/g')],[])
+AMI_USERS_LIST = $(if $(AMI_USERS),[$(shell echo '$(AMI_USERS)' | $(SED) 's/[[:space:]]//g' | $(SED) 's/[^,][^,]*/"&"/g')],[])
 
 IS_RELEASED ?= false
 ifeq ($(BUILDKITE_BRANCH),$(BUILDKITE_PIPELINE_DEFAULT_BRANCH))
@@ -117,7 +117,7 @@ packer-linux-amd64.output: $(PACKER_LINUX_FILES) build/fix-perms-linux-amd64
 			-var 'build_number=$(BUILDKITE_BUILD_NUMBER)' \
 			-var 'is_released=$(IS_RELEASED)' \
 			-var 'ami_public=$(AMI_PUBLIC)' \
-			-var 'ami_users=$(AMI_USERS_JSON)' \
+			-var 'ami_users=$(AMI_USERS_LIST)' \
 			buildkite-ami.pkr.hcl | tee $@
 
 build/linux-arm64-ami.txt: packer-linux-arm64.output env-AWS_REGION
@@ -154,7 +154,7 @@ packer-linux-arm64.output: $(PACKER_LINUX_FILES) build/fix-perms-linux-arm64
 			-var 'is_released=$(IS_RELEASED)' \
 			-var 'agent_version=$(CURRENT_AGENT_VERSION_LINUX)' \
 			-var 'ami_public=$(AMI_PUBLIC)' \
-			-var 'ami_users=$(AMI_USERS_JSON)' \
+			-var 'ami_users=$(AMI_USERS_LIST)' \
 			buildkite-ami.pkr.hcl | tee $@
 
 build/windows-amd64-ami.txt: packer-windows-amd64.output env-AWS_REGION
@@ -183,7 +183,7 @@ packer-windows-amd64.output: $(PACKER_WINDOWS_FILES)
 			-var 'is_released=$(IS_RELEASED)' \
 			-var 'agent_version=$(CURRENT_AGENT_VERSION_WINDOWS)' \
 			-var 'ami_public=$(AMI_PUBLIC)' \
-			-var 'ami_users=$(AMI_USERS_JSON)' \
+			-var 'ami_users=$(AMI_USERS_LIST)' \
 			buildkite-ami.pkr.hcl | tee $@
 
 # -----------------------------------------