Rogue pugixml-related files being installed

[ajm-ska]

Describe the bug
It has been noticed when we create a carta-backend RPM (and carta-backend Debian package), it makes and tries to install a bunch of pugixml related files. This should not happen because we only use pugixml as a third-party static dependency during build time. It should not be installing any files on the system.

For reference, the following is the error we get at the end of the rpmbuild stage listing the files in question:

Checking for unpackaged file(s): /usr/lib/rpm/check-files /root/rpmbuild/BUILDROOT/carta-backend-beta-4.0+2023.5.4-1.x86_64
error: Installed (but unpackaged) file(s) found:
   /usr/include/pugiconfig.hpp
   /usr/include/pugixml.hpp
   /usr/lib64/cmake/pugixml/pugixml-config-version.cmake
   /usr/lib64/cmake/pugixml/pugixml-config.cmake
   /usr/lib64/cmake/pugixml/pugixml-targets-release.cmake
   /usr/lib64/cmake/pugixml/pugixml-targets.cmake
   /usr/lib64/libpugixml.a
   /usr/lib64/pkgconfig/pugixml.pc

This problem was introduced when we began using pugixml as a third-party library in PR#1288

To Reproduce
Steps to reproduce the behavior:
(I haven't checked the following method, but I think it may work)

1. Build a carta-backend
2. Check the time stamp on/usr/lib64/libpugixml.a
3. It may indicate that the file was freshly installed.

Expected behavior
During the carta-backend make process, the third-party pugixml library should not install any files on your system.

Platform info (please complete the following information):

• OS [e.g. macOS Monterey]: CentOS7
• Browser [e.g. chrome, safari, electron app]: not applicable
• Browser version [e.g. 22]: not applicable
• Backend branch [e.g. dev, v3b2 release]: v4.0.0-beta.1
• Frontend branch [e.g. dev, v3b2 release]: not applicable