update-manager fails when other pro bins are available

[fcole90]

While attempting an upgrade with `sudo update-manager -dc` the program failed with the following error:

Unexpected error(s) occurred.
For more details, see the log: /var/log/ubuntu-advantage.log
To file a bug run: ubuntu-bug ubuntu-advantage-tools
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/UpdateManager/backend/InstallBackendAptdaemon.py", line 448, in _on_finished
    self._action_done(action,
  File "/usr/lib/python3/dist-packages/UpdateManager/backend/__init__.py", line 365, in _action_done
    self.window_main.start_available()
  File "/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py", line 241, in start_available
    self.refresh_cache()
  File "/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py", line 459, in refresh_cache
    self._get_ua_security_status()
  File "/usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py", line 285, in _get_ua_security_status
    s = json.load(p.stdout)
  File "/usr/lib/python3.10/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/usr/lib/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.10/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.10/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

I fixed it on my own machine by changing /usr/lib/python3/dist-packages/UpdateManager/UpdateManager.py at the function _get_ua_security_status, where running `pro security-status --format=json`, I replaced `pro` with `usr/bin/pro`. Apparently, there are other executables that may have that same name and not specifying the full path allows for name collisions.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: ubuntu-release-upgrader-core 1:22.04.19
ProcVersionSignature: Ubuntu 6.5.0-26.26~22.04.1-generic 6.5.13
Uname: Linux 6.5.0-26-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu82.5
Architecture: amd64
CasperMD5CheckResult: pass
CrashDB: ubuntu
CrashReports:
 640:1000:124:526616:2024-03-19 22:55:26.337597131 +0100:2024-03-19 22:55:27.337597131 +0100:/var/crash/_usr_bin_update-manager.1000.crash
 600:117:124:37:2024-03-19 23:09:00.739389126 +0100:2024-03-19 23:09:00.739389126 +0100:/var/crash/_usr_bin_update-manager.1000.uploaded
 664:1000:124:0:2024-03-19 23:08:59.043385432 +0100:2024-03-19 23:08:59.043385432 +0100:/var/crash/_usr_bin_update-manager.1000.upload
 640:0:124:103722:2024-03-20 18:46:35.799700926 +0100:2024-03-20 18:46:35.799700926 +0100:/var/crash/_usr_bin_update-manager.0.crash
CurrentDesktop: Unity
Date: Wed Mar 20 18:54:46 2024
InstallationDate: Installed on 2023-12-10 (101 days ago)
InstallationMedia: Ubuntu 22.04.3 LTS "Jammy Jellyfish" - Release amd64 (20230807.2)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nicolas Ramoudt (smoetje)]

The proposed fix solved the same exact problem here as well