meson: fix warning about configure_file() install kwarg

The install kwarg on configure_file() was only added in
Meson 0.50 but we're targetting older versions as well,
which caused a warning. The install kwarg is not needed
here as we specify install_dir, so we can just drop it.

Fixes #379
21 jobs for backport-mr-254-into-1.16-meson-configure-warning-with-older-meson-versions in 83 minutes and 35 seconds (queued for 1 minute and 44 seconds)
Status Job ID Name Coverage
  Preparation
passed #507817
gst indent

00:00:32

passed #507816
manifest

00:00:53

 
  Build
passed #507823
build cerbero android universal

00:13:00

passed #507824
build cerbero cross win32

00:08:22

passed #507825
build cerbero cross win64

00:05:51

passed #507822
build cerbero fedora x86_64

00:07:39

passed #507827
gst-ios-12.2
build cerbero ios universal

00:33:58

passed #507826
gst-macos-10.14
build cerbero macos x86_64

00:10:48

passed #507818
build fedora x86_64

00:05:57

passed #507819
build nodebug fedora x86_64

00:06:31

passed #507820
build static fedora x86_64

00:14:10

passed #507821
build static nodebug fedora x86_64

00:11:53

 
  Test
passed #507828
check fedora

00:03:48

passed #507829
integration testsuites fedora

00:08:32

passed #507834
valgrind bad

00:22:40

passed #507831
valgrind base

00:07:55

passed #507830
valgrind core

00:27:04

passed #507835
valgrind ges

00:04:38

passed #507832
valgrind good

00:24:11

passed #507833
valgrind ugly

00:02:35

 
  Integrate
passed #507836
android universal examples

00:09:01