dh with tempdir doesn't install into tempdir

We are using the following rule while doing builds for Synergy (https://github.com/symless/synergy-core).

> dh $@ --buildsystem=cmake --builddirectory=build -Pbuild/debian --parallel

It appears on 22.04, the temporary directory gets ignored at some point
and the project binaries get installed into the source debian directory.

This causes an empty-binary-packages warning and the deb is, in fact, empty.

Our current workaround is the remove the temporary directory flag.
However, I feel this is still a bug worth reporting.

----

When building on 20.04:

> Install the project...
> /usr/bin/cmake -P cmake_install.cmake
> -- Install configuration: "None"
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/share/icons/hicolor/scalable/apps/synergy.svg
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/share/applications/synergy.desktop
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/bin/synergyc
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/bin/synergys
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/bin/syntool
> -- Installing: /__w/synergy-core/synergy-core/build/debian/usr/bin/synergy

When building on 22.04:

> Install the project...
> /usr/bin/cmake -P cmake_install.cmake
> -- Install configuration: "None"
> -- Installing: /__w/synergy-core/synergy-> core/debian/synergy/usr/share/icons/hicolor/scalable/apps/synergy.svg
> -- Installing: /__w/synergy-core/synergy-core/debian/synergy/usr/share/applications/synergy.desktop
> -- Installing: /__w/synergy-core/synergy-core/debian/synergy/usr/bin/synergyc
> -- Installing: /__w/synergy-core/synergy-core/debian/synergy/usr/bin/synergys
> -- Installing: /__w/synergy-core/synergy-core/debian/synergy/usr/bin/syntool
> -- Installing: /__w/synergy-core/synergy-core/debian/synergy/usr/bin/synergy