meson: drop default-session-manager, use the first session-manager instead
Always pick the first -Dsession-manager
entry as the default one for the pw-uninstalled script.
Follow-up from !914 (comment 1053162), cc @pinkflames
Always pick the first -Dsession-manager
entry as the default one for the pw-uninstalled script.
Follow-up from !914 (comment 1053162), cc @pinkflames