Code completion in XML documentation comments missing

Type: Bug

Issue #4034 describes how code completion should be available within XML documentation comments. Well, it isn't. When I'm in such a `///` comment, the editor shows no intelligence whatsoever. Enter at the end of a line, I get a new empty line; the comment is not extended. `<` and the beginning of a tag name, nothing happens. I have to type it all the way from start to end and get no support. Sometimes I have to look up tags from Visual Studio projects or try out what works.

Extension version: 1.25.2
VS Code version: Code 1.74.3 (97dec172d3256f8ca4bfb2143f3f76b503ca0534, 2023-01-09T16:59:02.252Z)
OS version: Windows_NT x64 10.0.19045
Modes:
Sandboxed: No

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz (8 x 3400)|
|GPU Status|2d_canvas: enabled
canvas_oop_rasterization: disabled_off
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_renderer: enabled_on
video_decode: enabled
video_encode: enabled
vulkan: disabled_off
webgl: enabled
webgl2: enabled
webgpu: disabled_off|
|Load (avg)|undefined|
|Memory (System)|15.71GB (6.31GB free)|
|Process Argv|--folder-uri file:///c%3A/Source/Komprenu/Kappa-Indect/core-daemon-cs --crash-reporter-id 1b00a758-578c-4b77-a258-fe145c18e004|
|Screen Reader|no|
|VM|25%|

A/B Experiments

```
vsliv368cf:30146710
vsreu685:30147344
python383cf:30185419
vspor879:30202332
vspor708:30202333
vspor363:30204092
vslsvsres303:30308271
pythonvspyl392:30443607
vserr242cf:30382550
pythontb:30283811
vsjup518:30340749
pythonptprofiler:30281270
vshan820:30294714
vstes263cf:30335440
vscorecescf:30445987
pythondataviewer:30285071
vscod805:30301674
binariesv615:30325510
bridge0708:30335490
bridge0723:30353136
cmake_vspar411:30581797
vsaa593:30376534
pythonvs932:30410667
cppdebug:30492333
vsclangdf:30486550
c4g48928:30535728
dsvsc012cf:30540253
azure-dev_surveyone:30548225
pyindex848:30577860
nodejswelcome1cf:30587006
2e4cg342:30602488
89544117:30613380
fim-prod:30623723

```