Fix VSD max issues mask and tooltip
Original thread: https://gitlab.slack.com/archives/CJZR6KPB4/p1761254141553869
Problem
When we transitioned the VSD from the 3-month dora_chart visualization to the 6-month ai_impact_table visualization, we forgot to account for the max limit for the Issues closed metric. This was an edge case that required specialized logic in dora_chart, which was not patched into ai_impact_table before the migration.
Solution
Implement the 10000+ upper limit that was used on the VSD prior to the migration to ai_impact_table.