text-item: Don't use markup for matrix messages

The native matrix messages are already properly escaped, we don't want
to repeat it (which will result in markup like texts escaped again)

Reported by @joao.azevedo
7 jobs for wip/sadiq/fix-matrix-markup in 11 minutes and 38 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #366893
librem5
build-pureos-gcc-byzantium

00:03:11

 
  Test
passed #366895
librem5
check-po

00:00:27

passed #366894
librem5
test:debian-gcc

00:03:00

23.0%
 
  Package
passed #366896
librem5
package-pureos-byzantium

00:03:17

passed #366897
librem5:arm64
package-pureos-byzantium:arm64

00:05:26

 
  Test Package
passed #366898
librem5
autopkgtest-pureos-byzantium-package

00:01:15

passed #366899
librem5
lintian-pureos-byzantium-package

00:01:03