fence_aws in Focal and Bionic (LP: #1894323) don't behave the same.

After the SRU of LP: #1894323, it looks like a bad behavior in pacemaker Bionic was exposed:

When declaring the fence_aws primitive, you can either declare it as a single resource and describe the pcmk_host_map... OR you can declare one fence resource PER NODE doing the exact same thing BUT using the "plug/port" resource argument. The thing is... in Focal, both methods work but in Bionic, the second method does not work.

It is not a big deal as there are some fence agents designed to work with "pcmk_host_map" only, and some others are designed to work with "plug/port" argument.

Test case (BIONIC):

Using the fence-agents version from LP: #1894323 you first configure the fence_aws primitive as:

```
node 1: bionic01
node 2: bionic02
node 3: bionic03

primitive fence-bionic stonith:fence_aws \
 params \
    access_key="xxxx" \
    secret_key="yyyy" \
    region="us-east-1" \
    pcmk_host_map="bionic01:i-068e134;bionic02:i-0136edd;bionic03:i-0de279ab"
```
and

```
property cib-bootstrap-options: \
    have-watchdog=false \
    dc-version=1.1.18-2b07d5c5a9 \
    cluster-infrastructure=corosync \
    stonith-enabled=on \
    stonith-action=reboot \
    no-quorum-policy=stop \
    cluster-name=bionic
```

You can cause an issue in the interconnect and observe the fence_aws agent working properly. Then, stop the resource and remove it. Configure the fencing agent as 1 fence resource per node:

```
primitive fence-bionic01 stonith:fence_aws \
 params \
    access_key="xxxx" \
    secret_key="yyyy" \
    region="us-east-1" \
    pcmk_host_map="bionic01:i-068e134;bionic02:i-0136edd;bionic03:i-0de279ab" \
    plug="bionic01:i-068e134de1beddc7f"

primitive fence-bionic02 stonith:fence_aws \
 params \
    access_key="xxxx" \
    secret_key="yyyy" \
    region="us-east-1" \
    pcmk_host_map="bionic01:i-068e134;bionic02:i-0136edd;bionic03:i-0de279ab" \
    plug="bionic02:i-0136eddd045ceb7e2"

primitive fence-bionic03 stonith:fence_aws \
 params \
    access_key="xxxx" \
    secret_key="yyyy" \
    region="us-east-1" \
    pcmk_host_map="bionic01:i-068e134;bionic02:i-0136edd;bionic03:i-0de279ab" \
    plug="bionic03:i-0de279ab4e6d642c8"

location l-fence-bionic01 fence-bionic01 -inf: bionic01
location l-fence-bionic02 fence-bionic02 -inf: bionic02
location l-fence-bionic03 fence-bionic03 -inf: bionic03
```

This last example, using multiple fence resources, works in Focal but does not work in Bionic (after making sure both had the exact same fence_aws script version in bug LP: #1894323).

I think a bisection of pacemaker between Bionic and Focal (yes, its bad because its a major version change) might be needed here to understand why using "plug" does not work in Bionic.

Looks like Red Hat also faces the same issue at:

https://access.redhat.com/solutions/4642491

Note: I have exhaustively tested the "pcmk_host_map" only primitive and it worked fine (fencing the correct nodes all the times I fenced the cluster). Using plug "" in Bionic is not advised as fence_aws fences other nodes (than the one provided in plug argument).