build: Remove libdconf-common-hidden

`libdconf-common-hidden` is built to hide symbols not necessary
in the `gsettings` gio module that only needs to expose
`g_io_module_[load|query|unload]` symbols.

To achieve this a symbol map along with `version-script` linker flag
is used. Thanks to this only the necessary symbols are exposed,
building `libdconf-common-hidden` static library is not necessary
anymore and the existing dependencies can be used.
2 jobs for fix-symbols in 2 minutes and 24 seconds (queued for 5 minutes and 49 seconds)
latest
Status Job ID Name Coverage
  Build
passed #84132
build-job

00:01:07

 
  Test
passed #84133
test

00:01:16