cmd/pprof: graphviz node names are funny with generics [1.19 backport]

[gopherbot]

@prattmic requested issue #54105 to be considered for backport to the next 1.19 minor release.

@gopherbot Please backport to 1.19. This fix just barely missed 1.19. While it does have a workaround (use upstream pprof instead of go tool pprof), that is unlikely to be clear to users, and the fix is simple.

[prattmic]

Note that we are backporting an update of github.com/google/pprof. This update CL includes two pprof changes (google/pprof@d04f242 and google/pprof@a41b82a). Only the latter is needed to fix the bug, but IMO the other is safe enough that it is not worth creating a custom backport CL to avoid that commit.

[gopherbot]

Change https://go.dev/cl/423356 mentions this issue: [release-branch.go1.19] cmd: vendor github.com/google/pprof to fix mangled type parameter symbol names

[gopherbot]

Closed by merging 2375ef8 to release-branch.go1.19.