Drop coverage build intermediates before running the tests

docker system df shows buildPortableLibdatadogPhp leaves 5.97G of
coverage-instrumented cargo intermediates in php-portable-libdatadog-php,
which together with the pulled images puts the ~20G Docker host storage at
18G/93% before a single test runs. The tests then take it to 100%, and a full
disk is what breaks RaspSqliTests: InnoDB reports "Error number 28 means 'No
space left on device'".

The build copies libdatadog_php.so out of the target directory and both the
tests and the coverage report consume that copy, so the intermediates are dead
weight afterwards. This volume is also not part of loadCaches/saveCaches, so
nothing in a later job reuses them. Removing them frees ~6G before the tests
start. Done in the job script rather than the Gradle task so local incremental
rebuilds are unaffected.

Author: cataphract

.gitlab/generate-appsec.php

@@ -305,6 +305,19 @@
       TERM=dumb ./gradlew buildPortableLibdatadogPhp \
         --info -Pbuildscan --scan -PuseHelperRustCoverage
       report_docker_disk 'after buildPortableLibdatadogPhp'
+
+      # Coverage-instrumented artifacts are bulky: this leaves ~6G of cargo
+      # intermediates in php-portable-libdatadog-php, over a quarter of the
+      # ~20G available, and the tests then run the disk out. The build copies
+      # libdatadog_php.so out of the target directory, and that copy is what
+      # both the tests and the coverage report use, so the intermediates are
+      # dead weight from here on. Unlike the cargo caches, this volume is not
+      # part of loadCaches/saveCaches, so nothing later reuses them either.
+      # Dropped here rather than in the Gradle task so local incremental
+      # rebuilds keep working.
+      docker run --rm -v php-portable-libdatadog-php:/vol alpine \
+        rm -rf /vol/cargo-target
+      report_docker_disk 'after dropping build intermediates'
       TERM=dumb ./gradlew test8.3-release-ssi test8.4-release-zts-ssi \
         --info -Pbuildscan --scan -PcheckCoreDumps -PuseHelperRustCoverage
       report_docker_disk 'after tests'