[vs18.6] Fix OptProf bootstrapper channel: use 'int.stable' not 'release'

[JanProvaznik]

Problem

The previous fix (#13992, stable -> release) was wrong. On the official build it fails with:

##[error]Invalid JSON primitive: .

because release is not a valid channel moniker for VS 18. https://aka.ms/vs/18/release/channel bounces to a Bing fallback page, which the bootstrapper task saves as the .chman and then fails to parse as JSON.

Why release and stable are both wrong

The aka.ms moniker convention changed between VS17 and VS18:

moniker	VS 17	VS 18
release	real CDN manifest	bounces to bing.com (broken)
stable	bounces to bing.com	real public CDN manifest (VisualStudio.18.Release.chman)
int.stable	n/a	internal vsdrop manifest (VisualStudio.18.int.stable.chman)

So for VS 18 the public GA channel is stable (not release). But the MicroBuild MicroBuildBuildVSBootstrapper task's CreateConfigFile only special-cases the VS17-era public names release/preview. Any other name — including stable — is routed down the internal path, where it parses the installer-manifest URL as a vsdrop {prefix};{suffix} drop. stable's public CDN URL has no semicolon, hence the original "drop url ... is invalid" failure.

Fix

Use int.stable: the internal, vsdrop-backed equivalent of stable. It tracks the stable 18.x bits (not the moving int.main that caused the System.Text.Json 10.0.0.4 drift in #13923), and because it is an internal channel its installer-manifest URL is a vsdrop {prefix};{suffix} URL that CreateConfigFile accepts.

• https://aka.ms/vs/18/int.stable/channel resolves to VisualStudio.18.int.stable.chman on vsdrop.microsoft.com (verified).

Relevant task logic (CreateConfigFile): https://dev.azure.com/devdiv/Engineering/_git/MicroBuild?path=/src/Tasks/BuildVSBootstrapper/plugin.ps1&line=286&lineEnd=307&lineStartColumn=1&lineEndColumn=1&lineStyle=plain&_a=contents

Companion to #14006 (vs18.7).

---

Local validation (verified before merge)

Replicated every step the MicroBuildBuildVSBootstrapper task performs, using the same VSDrop token audience the task uses (per plugin.ps1):

Check	Result	Failure mode it rules out
(a) aka.ms/vs/18/int.stable/channel redirects to vsdrop (not bing.com)	✅	the release "Invalid JSON primitive" (Bing fallback page)
(b) .chman downloads and is valid JSON (11 channelItems)	✅	the release "Invalid JSON primitive"
(c) installer-manifest URL splits into {prefix};{suffix} (2 parts)	✅	the stable "drop url ... is invalid" (CreateConfigFile Split(";") check)
(d) config payload …;bootstrappers/Enterprise/configuration/vs_setup_bootstrapper.config returns HTTP 200 (after the corp→ZTN host rewrite the task does)	✅	the only downstream config-download risk
(bonus) installer .vsman downloads and parses (20,527 packages)	✅	the vsman overlay step input

This is the same code path int.main already runs successfully; int.stable only pins it to stable 18.x bits.

Note: the int.stable channel's installer manifest is named VisualStudioIntPreview.vsman (...Channels.IntPreviewInstallerManifest). That is just the drop's internal naming for the stable-pinned channel and does not affect correctness — all checks above passed.

[Copilot]

Pull request overview

Updates the OptProf Visual Studio bootstrapper configuration for the VS 18.6 pipeline to use a VS18-valid internal channel moniker so the MicroBuild bootstrapper task can resolve and parse the channel manifest correctly.

Changes:

• Change VisualStudio.ChannelName from 'release' to 'int.stable' for VS 18 builds.
• Ensure MicroBuildBuildVSBootstrapper@3 receives the updated channel name via channelName: $(VisualStudio.ChannelName).