Amend chainspecs for `people-westend` and add IBP bootnodes (#4072)

Dear team, dear @NachoPal @joepetrowski @bkchr @ggwpez

,

This is a retry of #3957, after merging master as advised!,

Many thanks!

**_Milos_**

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>

prdoc/pr_4072.prdoc

+title: "Amend chainspecs for people-westend and add IBP bootnodes"
+
+doc:
+  - audience: Node Operator
+    description: |
+      Fixes the people-westend chain spec.
+
+crates:
+  - name: polkadot-parachain-bin
+    bump: patch