wayland/text-input: Open the OSK after setting input focus

Otherwise the OSK remains closed when only a single
zwp_text_input_v3.enable request for a given surface is received from
a client.

The previous behavior required focusing (or pressing) text input boxes
twice for the OSK to open.

This undoes a part of eabb7893 which doesn't appear to be
necessary to accomplish its purpose of keeping the OSK open on input
focus change within a surface.

Closes: #1506

!1543
7 jobs for !1543 with text-input-enable in 11 minutes and 38 seconds (queued for 1 second)
latest detached
Status Job ID Name Coverage
  Review
passed #965299
check-commit-log

00:00:24

 
  Build
passed #965300
build-mutter

00:02:37

passed #965302
build-without-native-backend-and-wayland

00:02:02

passed #965301
build-without-opengl-and-glx

00:02:15

 
  Test
passed #965304
can-build-gnome-shell

00:02:02

passed #965303
test-mutter

00:04:55

 
  Coverage
passed #965305
test-mutter-coverage

00:04:05

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