[mongodb] Upgrade ECS to 8.0.0

[r00tu53r]

Automated PR.

Upgrades ECS to 8.0.0.

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[elasticmachine]

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Build stats

• Start Time: 2022-01-11T04:41:27.679+0000

• Duration: 14 min 43 sec

• Commit: e395c3e

Test stats 🧪

Test	Results
Failed	0
Passed	29
Skipped	0
Total	29

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[jsoriano]

Is this change needed? (asked too in the meta issue #2363 (comment))