Fix: Environment kv editor flash when user input the first time [INS-4709]

[cwangsmv]

Changes:

• Add a useMemo hook so that empty environment data will generate same pair data
• Allow user to delete the item if there's only one item exists

Closes INS-4698
Closes INS-4709

[sentry-io]

Suspect Issues

This pull request was deployed and Sentry observed the following issues:

• ‼️ Error: Expected fetch controller: :r30: app:https:///index.html View Issue
• ‼️ Error: Expected fetch controller: :r1b: app:https:///index.html View Issue
• ‼️ Error: Expected fetch controller: :r30: app:https:///index.html View Issue
• ‼️ Error: Expected fetch controller: :r30: app:https:///index.html View Issue
• ‼️ Error: Expected fetch controller: :r7: app:https:///index.html View Issue

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