doc: remove appmetrics from tierlist

PR-URL: #43608
Reviewed-By: Beth Griggs <bgriggs@redhat.com>
Reviewed-By: Michael Dawson <mhdawson@ibm.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Gerhard St<C3><B6>bich <deb2001-github@yahoo.de>

Author: tony-go

doc/contributing/diagnostic-tooling-support-tiers.md

@@ -134,5 +134,4 @@ The tools are currently assigned to Tiers as follows:
 | Debugger  | Command line Debug Client | ?                             | Yes                     | 1           |
 | Tracing   | trace\_events (API)       | No                            | Yes                     | 1           |
 | Tracing   | trace\_gc                 | No                            | Yes                     | 1           |
-| F/P/T     | appmetrics                | No                            | No                      | ?           |
 | M/T       | eBPF tracing tool         | No                            | No                      | ?           |