Remove deprecated rule references

Author: shashank-elastic

docs/detections/prebuilt-rules/downloadable-packages/8-19-4/prebuilt-rules-8-19-4-appendix.asciidoc

@@ -74,4 +74,3 @@ include::prebuilt-rule-8-19-4-potential-powershell-obfuscation-via-string-concat
 include::prebuilt-rule-8-19-4-potential-powershell-obfuscation-via-string-reordering.asciidoc[]
 include::prebuilt-rule-8-19-4-potential-powershell-obfuscation-via-special-character-overuse.asciidoc[]
 include::prebuilt-rule-8-19-4-potential-malicious-powershell-based-on-alert-correlation.asciidoc[]
-include::prebuilt-rule-8-19-4-deprecated-azure-entra-sign-in-brute-force-microsoft-365-accounts-by-repeat-source.asciidoc[]

docs/detections/prebuilt-rules/downloadable-packages/8-19-4/prebuilt-rules-8-19-4-summary.asciidoc

@@ -149,6 +149,4 @@ This section lists all updates associated with version 8.19.4 of the Fleet integ
 
 |<<prebuilt-rule-8-19-4-potential-malicious-powershell-based-on-alert-correlation, Potential Malicious PowerShell Based on Alert Correlation>> | Identifies PowerShell script blocks associated with multiple distinct detections, indicating likely malicious behavior. | update | 2 
 
-|<<prebuilt-rule-8-19-4-deprecated-azure-entra-sign-in-brute-force-microsoft-365-accounts-by-repeat-source, Deprecated - Azure Entra Sign-in Brute Force Microsoft 365 Accounts by Repeat Source>> | Identifies potential brute-force attempts against Microsoft 365 user accounts by detecting a high number of failed interactive or non-interactive login attempts within a 30-minute window from a single source. Attackers may attempt to brute force user accounts to gain unauthorized access to Microsoft 365 services via different services such as Exchange, SharePoint, or Teams. | deprecated | 4 
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