ci: windows: Use CIRRUS_ESCAPING_PROCESSES, revert 770011e.

cirrus-ci now defaults to killing processes still running at the end of a
script. Unfortunately we start postgres in the background, which seems
nontrivial to fix. Previously we worked around that in 770011e by using an
older agent version, but now that CIRRUS_ESCAPING_PROCESSES we should use that.

This reverts commit 770011e "ci: windows:
Work around cirrus-ci bug causing test failures.

Discussion: https://postgr.es/m/CA+hUKGKx7k14n2nAALSvv6M_AB6oHasNBA65X6Dvo8hwfi9y0A@mail.gmail.com

Author: anarazel

.cirrus.yml

@@ -375,11 +375,12 @@ task:
     # "suites".
     T_C: "\"C:/Program Files/Git/usr/bin/timeout.exe\" -v -k60s 15m"
 
-    # Temporarily work around cirrus-ci bug causing processes started from a
-    # script to be killed, even if intentionally running in background. See
-    # https://github.com/cirruslabs/cirrus-ci-agent/issues/218
-    # https://postgr.es/m/CA%2BhUKGKx7k14n2nAALSvv6M_AB6oHasNBA65X6Dvo8hwfi9y0A%40mail.gmail.com
-    CIRRUS_AGENT_VERSION: 1.73.2
+    # startcreate_script starts a postgres instance that we don't want to get
+    # killed at the end of that script (it's stopped in stop_script). Can't
+    # trivially use background_scripts because a) need pg_ctl's dropping of
+    # permissions b) need to wait for startup to have finished, and we don't
+    # currently have a tool for that...
+    CIRRUS_ESCAPING_PROCESSES: 1
 
   only_if: $CIRRUS_CHANGE_MESSAGE !=~ '.*\nci-os-only:.*' || $CIRRUS_CHANGE_MESSAGE =~ '.*\nci-os-only:[^\n]*windows.*'