Make build scripts handle default settings.xml correctly

Wrong behaviour in EAP 7.1.0.DR12

• mvnw, build.sh and integration-tests.sh does't use productized settings.xml by default.

Desired behaviour

• mvnw, build.sh and integration-tests.sh should use productized settings.xml by default.

Workaround for build.sh
Productized settings.xml needs to be defined manually by "-s" maven property, example:
./build.sh clean -Dmaven.repo.local=$NEW_REPO -DallTests -Djboss.test.mixed.domain.dir=${HUDSON_STATIC_ENV}/eap/archives-repository/mixed-domain -s tools/maven/conf/settings.xml

Workaround for integration-tests.sh
Absolute path needs to be used (see JBEAP-8947), example: "-s /mnt/hudson_workspace/mkopecky/ts/tools/maven/conf/settings.xml"

Additional information:

• productized settings.xml is added in this productization commit
• "tools/maven/conf/settings.xml" location doesn't make sense, because download-maven.sh script was removed. But I recommend to keep current location because of backward compatibility