github: run asan build on fedora36

Problem: The address sanitizer CI build started failing for unknown
reason. The failure is occurring in the make program before even running
any tests in 'make check.'

Take the following steps to attempt to address the issue:

 - The asan build currently runs on Fedora 34, which is getting old
   at this point. Update the sanitizer run to use Fedora 36.

 - Drop the LD_PRELOAD of the libasan library, which seems to be
   causing the failure in some unrelated programs not compiled with
   -fsanitize=address (a guess).

 - Add 'verify_asan_link_order=false' to ASAN_OPTIONS to avoid libasan
   complaints about link order. This is only important if malloc, free,
   etc., are replaced by libs. In that case libasan _must_ be first in
   the link order.
   See https://github.com/google/sanitizers/wiki/AddressSanitizerFlags

 - Update -j2 to -j4 (github runners now have 4 vcpus)

.github/workflows/asan.yml

@@ -14,13 +14,12 @@ jobs:
     - name: docker-run-checks with ASan
       timeout-minutes: 40
       env:
-        PRELOAD: /usr/lib64/libasan.so.6
-        ASAN_OPTIONS: detect_leaks=0,start_deactivated=true,replace_str=true
+        ASAN_OPTIONS: detect_leaks=0,start_deactivated=true,replace_str=true,verify_asan_link_order=false
         FLUX_TEST_TIMEOUT: 300
         TAP_DRIVER_QUIET: t
       run: >
         src/test/docker/docker-run-checks.sh \
-          --image=fedora34 --unit-test-only -j2 \
+          --image=fedora36 --unit-test-only -j4 \
           -- --with-flux-security --enable-sanitizer=address
 
     - name: after failure