Maven 3.9 resolver ignores proxy configured via MAVEN_OPTS

The new native resolver seems to no longer respect HTTP/S proxy configuration set as options via `MAVEN_OPTS`. I haven't tried if this also happens when supplying the options directly via CLI as well, I assume that might be the case?

Sample GitLab CI script that worked with 3.8.7 but now fails with 3.9:

image: maven:3.9

build:
  variables:
    MAVEN_OPTS: >-
      -Dhttp.proxyHost=$PROXY_HOST
      -Dhttp.proxyPort=$PROXY_PORT 
      -Dhttps.proxyHost=$PROXY_HOST
      -Dhttps.proxyPort=$PROXY_PORT
      -Dhttp.nonProxyHosts=$NO_PROXY_HOSTS
  script:
    - mvn clean install

Likely introduced in https://github.com/apache/maven/pull/892.