Markdown renderer unescape is not totally fixed

Issue Type: <b>Bug</b> I found [this existing issue](https://github.com/microsoft/vscode/issues/14968) about Markdown renderer escapes, which was supposed to be fixed, but found an edge case that is still broken. Load [this repro](https://github.com/thw0rted/issue-examples/tree/vscode-json-schema) in Code, then mouse over the "value" property name in `data.jsonc`. You will see that the link ends with a superfluous literal backslash character, and clicking it opens a URL that ends with `%5C`.  ---- VS Code version: Code 1.62.2 (3a6960b964327f0e3882ce18fcebd07ed191b316, 2021-11-11T20:56:38.428Z) OS version: Windows_NT x64 10.0.19043 Restricted Mode: No <details> <summary>System Info</summary> |Item|Value| |---|---| |CPUs|Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz (8 x 2112)| |GPU Status|2d_canvas: enabled<br>gpu_compositing: enabled<br>multiple_raster_threads: enabled_on<br>oop_rasterization: enabled<br>opengl: enabled_on<br>rasterization: enabled<br>skia_renderer: enabled_on<br>video_decode: enabled<br>vulkan: disabled_off<br>webgl: enabled<br>webgl2: enabled| |Load (avg)|undefined| |Memory (System)|15.92GB (2.87GB free)| |Process Argv|--crash-reporter-id 104bab69-2434-4424-a670-b65cf70439b5| |Screen Reader|no| |VM|0%| </details><details><summary>Extensions (20)</summary> Extension|Author (truncated)|Version ---|---|--- vscode-m3u|af4|1.0.0 ng-template|Ang|13.0.0 npm-intellisense|chr|1.4.0 vscode-svgviewer|css|2.0.0 vscode-markdownlint|Dav|0.45.0 githistory|don|0.6.19 xml|Dot|2.5.1 EditorConfig|Edi|0.16.4 vscode-npm-script|eg2|0.3.23 json-tools|eri|1.0.2 JasmineSnippets|jor|0.1.0 xml-format|mik|1.1.2 remote-ssh|ms-|0.66.1 remote-ssh-edit|ms-|0.66.1 powershell|ms-|2021.10.2 java|red|1.0.0 vscode-autohotkey|sle|0.2.2 vscode-hexdump|sle|1.8.1 vscodeintellicode|Vis|1.2.14 html-css-class-completion|Zig|1.20.0 </details> <!-- generated by issue reporter -->