ci: Add missing "set -e" to scripts run by su.

If any shell command fails, the whole script should fail.  To avoid
future omissions, add this even for single-command scripts that use su
with heredoc syntax, as they might be extended or copied-and-pasted.

Extracted from a larger patch that wanted to use #error during
compilation, leading to the diagnosis of this problem.

Reviewed-by: Tristan Partin <tristan@partin.io> (earlier version)
Discussion: https://postgr.es/m/DDZP25P4VZ48.3LWMZBGA1K9RH%40partin.io
Backpatch-through: 15

.cirrus.tasks.yml

@@ -94,6 +94,7 @@ task:
 
   configure_script: |
     su postgres <<-EOF
+      set -e
       meson setup \
         --buildtype=debug \
         --auto-features=disabled \
@@ -102,6 +103,7 @@ task:
     EOF
   build_script: |
     su postgres <<-EOF
+      set -e
       ninja -C build -j${BUILD_JOBS} ${MBUILD_TARGET}
     EOF
   upload_caches: ccache
@@ -111,6 +113,7 @@ task:
   # tap test that exercises both a frontend binary and the backend.
   test_minimal_script: |
     su postgres <<-EOF
+      set -e
       ulimit -c unlimited
       meson test $MTEST_ARGS --num-processes ${TEST_JOBS} \
         tmp_install cube/regress pg_ctl/001_start_stop
@@ -172,6 +175,7 @@ task:
   # already takes longer than other platforms except for windows.
   configure_script: |
     su postgres <<-EOF
+      set -e
       meson setup \
         --buildtype=debug \
         -Dcassert=true -Duuid=bsd -Dtcl_version=tcl86 -Ddtrace=auto \
@@ -184,6 +188,7 @@ task:
 
   test_world_script: |
     su postgres <<-EOF
+      set -e
       ulimit -c unlimited
       meson test $MTEST_ARGS --num-processes ${TEST_JOBS}
     EOF
@@ -208,6 +213,7 @@ task:
     # during upload, as it doesn't expect artifacts to change size
     stop_running_script: |
       su postgres <<-EOF
+        set -e
         build/tmp_install/usr/local/pgsql/bin/pg_ctl -D build/runningcheck stop || true
       EOF
     <<: *on_failure_meson
@@ -328,6 +334,7 @@ task:
       # that.
       configure_script: |
         su postgres <<-EOF
+          set -e
           ./configure \
             --enable-cassert --enable-debug --enable-tap-tests \
             --enable-nls \
@@ -342,6 +349,7 @@ task:
 
       test_world_script: |
         su postgres <<-EOF
+          set -e
           ulimit -c unlimited # default is 0
           make -s ${CHECK} ${CHECKFLAGS} -j${TEST_JOBS}
         EOF
@@ -357,6 +365,7 @@ task:
 
       configure_script: |
         su postgres <<-EOF
+          set -e
           meson setup \
             --buildtype=debug \
             -Dcassert=true \
@@ -369,6 +378,7 @@ task:
       # locally.
       configure_32_script: |
         su postgres <<-EOF
+          set -e
           export CC='ccache gcc -m32'
           meson setup \
             --buildtype=debug \
@@ -388,6 +398,7 @@ task:
 
       test_world_script: |
         su postgres <<-EOF
+          set -e
           ulimit -c unlimited
           meson test $MTEST_ARGS --num-processes ${TEST_JOBS}
         EOF
@@ -400,6 +411,7 @@ task:
       # from C, prevent that with PYTHONCOERCECLOCALE.
       test_world_32_script: |
         su postgres <<-EOF
+          set -e
           ulimit -c unlimited
           PYTHONCOERCECLOCALE=0 LANG=C meson test $MTEST_ARGS -C build-32 --num-processes ${TEST_JOBS}
         EOF