Removed setting debug info identity API]

Summary: As I removed all usages no one left who needs it

Differential Revision: D68817856

fbshipit-source-id: d1351e660fdf31d4266a62995dc938897e5be82e

prelude/debugging/labels.bzl

@@ -21,44 +21,6 @@ DBG_INFO_EXEC = "dbg:info:exec"
 # specific information that help debugging tools to properly configure a debugger. (Support for any given language/rule needs to be implemented in fdb.bxl)
 DBG_INFO_REF = "dbg:info:ref"
 
-# Certain dependency graphs may have convoluted setup:
-#                    ┌───────────────────────────┐
-#                    │        //my:binary        │
-#                    └───────────────────────────┘
-#                            /            \
-#                           /              \
-#  ┌───────────────────────────┐   ┌───────────────────────────┐
-#  │     //third-party:absl    │   │  //third-party:absl_base  │
-#  └───────────────────────────┘   └───────────────────────────┘
-#               │                   /            │
-#               │                  /             │
-#  ┌───────────────────────────────┐    ┌─────────────────────────────────┐
-#  │ //third-party:absl_baseFbcode │    │ //third-party:absl_helperFbcode │
-#  └───────────────────────────────┘    └─────────────────────────────────┘
-#
-# `:absl_base` and `:absl_baseFbcode` are mirrored targets with the same
-# source files where "Fbcode" suffixed target is generated.  If `absl_base`
-# defines `preferred_linkage = "static"` then duplicated `.o`  files are
-# being linked together. That works fine because we pass `--as-needed` and
-# linker knows how to drop duplicated symbols. With "packed" or "merged"
-# split-dwarf we then producing `.dwo` file from executable and it works fine.
-#
-# The problem arises with "unpacked" (or "split") split-dwarf that produces
-# `.dwo` files that are packed together via `llvm-dwp` tool. Unfortunately,
-# `llvm-dwp` doesn't know how to deal with duplicates and always fail hard.
-#
-# As a workaround, we marking debug symbols in `absl_base` and `absl_baseFbcode`
-# with the same `absl_base` identity and filtering out duplicates ourselves
-# before passing list of `.dwo` files to `llvm-dwp` tool.
-#
-# llvm-20 seems to produce different debug units with different IDs by filepahts
-# and doesn't have this issue. We may drop this workaround once llvm-20 is widely used.
-#
-DBG_INFO_IDENTITY = "dbg:info:identity"
-
-def dbg_info_identity(target_label: str) -> list[str]:
-    return ["{}={}".format(DBG_INFO_IDENTITY, target_label)]
-
 def dbg_info_exec(target_label) -> list[str]:
     return ["{}={}".format(DBG_INFO_EXEC, target_label)]