RFR: 8335: Duplicate values in tooltip for RSS and RSS (Peak) in memory tab

[Aymane Harmaz]

This PR makes sure, we do not add attributes twice to the same renderer on the memory page

The issue : 
- The supplier used for merging events was having a side effect (calls to methods adding attributes to the same renderer) 
- The supplier was consumed twice leading to the side effect being executed twice and that is mainly what causes the tooltip to contain duplicated attributes on the memory page 

The following screenshots respectively show the tooltips before and after the change

<img width="1082" height="375" alt="tooltip-before" src="https://github.com/user-attachments/assets/824b883d-6941-4100-9d90-54bb4e184aaa" />

<img width="1308" height="277" alt="tooltip-fixed" src="https://github.com/user-attachments/assets/505cdcf3-1d70-4c6d-a195-325614e405d0" />

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Commit messages:
 - 8335: Duplicate values in tooltip for RSS and RSS (Peak) in memory tab

Changes: https://git.openjdk.org/jmc/pull/685/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=685&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8335
  Stats: 6 lines in 1 file changed: 4 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jmc/pull/685.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/685/head:pull/685

PR: https://git.openjdk.org/jmc/pull/685