Recurring ambiguous "node number" wording still causes mistranslation (JA)

What is changed, added or deleted? (Required)

In #20549 / #20811, "node number" was replaced with "node count" in tidb-cloud/size-your-cluster.md because "node number" reads as "the specific identification/label given to each instance" rather than "the quantity of instances". That fix was scoped to a single file, but the same ambiguous phrasing still appears throughout the corpus and has already caused at least one real Japanese mistranslation (release-notes-2023.md translated it as "ノード番号" / "node ID" instead of "ノード数" / "node count").

Remaining occurrences of "node number" (as of release-8.5) that likely need the same "node count" / "number of nodes" treatment:

• functions-and-operators/group-by-modifier.md:47 — link text [Change node number]
• tidb-cloud/backup-and-restore.md:312,340
• tidb-cloud/monitor-built-in-alerting.md:94-105 (12 occurrences, alert-rule table)
• tidb-cloud/releases/notification-2023-11-14-scale-feature-maintenance.md:22
• tidb-cloud/releases/release-notes-2023.md:901
• tidb-cloud/scalability-concepts.md:30,36,42
• tidb-cloud/scale-tidb-cluster.md:25,29,35 (including the ## Change node number heading)
• tidb-cloud/terraform-use-cluster-resource.md:268
• tidb-cloud/tiproxy-management.md:29 ("node numbers")

Suggest replacing with "node count" (matching the precedent in #20811) or "the number of ... nodes" for prose, and "Change node count" for the heading/link text.

Which TiDB version(s) do your changes apply to? (Required)

• master (the latest development version)

What is the related PR or file link(s)?

• Other reference link(s): follow-up to #20549 and #20811

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

Start by comparing the wording in tidb-cloud/size-your-cluster.md with the precedent from #20811, then inspect the listed occurrences in functions-and-operators/group-by-modifier.md, tidb-cloud/backup-and-restore.md, and the other named files. Update ambiguous uses of “node number” where they mean quantity, preserving the suggested heading and link wording. Done means the listed corpus no longer uses the ambiguous phrasing for node counts.