build: dist: defer PlainSourceTarball

Apparently it changes some tool sources and invalidates their fingerprints, forcing us to build them several times (before and after vendoring sources).
I have not dug into why vendoring actually invalidates the figreprints, but the moving the vendoring lower in the pipeline seems to avoid the issue.
I could imagine that we somehow write a .cargo/config somewhere which somehow makes subsequent builds use the vendored deps but I was not able to find anything.

I checked the sizes of generated archives pre and post patch and their are the same, so I hope there is not functional change.

Fixes rust-lang#93033

src/bootstrap/builder.rs

@@ -495,7 +495,6 @@ impl<'a> Builder<'a> {
                 dist::RustcDev,
                 dist::Analysis,
                 dist::Src,
-                dist::PlainSourceTarball,
                 dist::Cargo,
                 dist::Rls,
                 dist::RustAnalyzer,
@@ -506,6 +505,11 @@ impl<'a> Builder<'a> {
                 dist::LlvmTools,
                 dist::RustDev,
                 dist::Extended,
+                // It seems that PlainSourceTarball somehow changes how some of the tools
+                // perceive their dependencies (see #93033) which would invaliate fingerprints
+                // and force us to rebuild tools after vendoring dependencies.
+                // To work around this, create the Tarball after building all the tools.
+                dist::PlainSourceTarball,
                 dist::BuildManifest,
                 dist::ReproducibleArtifacts,
             ),