Update Dockerfile to use variable GIT_REPO from config

Author: ajorquera

deployment/ecr/prebid-server/Dockerfile

@@ -43,7 +43,7 @@ java.net.http,java.security.sasl,jdk.naming.dns,jdk.crypto.ec,jdk.security.auth
 COPY docker-build-config.json docker-build-config.json
 
 # Clone and build in single layer to reduce size
-RUN git clone --single-branch --branch master --depth 1 https://github.com/prebid/prebid-server-java.git && \
+RUN git clone --single-branch --branch master --depth 1 $(jq -r .GIT_REPO ./docker-build-config.json) && \
     cd prebid-server-java && \
     git fetch origin --tags && \
     git checkout $(jq -r .GIT_TAG_VERSION ../docker-build-config.json) && \

deployment/ecr/prebid-server/docker-build-config.json

@@ -1,5 +1,5 @@
 {
+  "GIT_REPO": "https://github.com/prebid/prebid-server-java.git",
   "GIT_TAG_VERSION": "3.22.0",
   "MVN_CLI_OPTIONS": "-Dmaven.test.skip"
-}
-
+}