deprecate azure data lake storage gen1 for external data + external t…

[lior1990]

…able

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Learn Build status updates of commit 7f0075b:

✅ Validation status: passed

File	Status	Preview URL	Details
data-explorer/external-tables-managed-identities.md	✅Succeeded
data-explorer/kusto/api/connection-strings/storage-connection-strings.md	✅Succeeded
data-explorer/kusto/management/external-tables-azure-storage.md	✅Succeeded
data-explorer/kusto/management/external-tables-delta-lake.md	✅Succeeded
data-explorer/kusto/query/externaldata-operator.md	✅Succeeded

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[v-regandowner]

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[lior1990]

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[v-dirichards]

@spelluru

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