[Revalidation] Skip packages with many versions

[loic-sharma]

This change allows the revalidation job to skip packages with many versions. This generates the following query:

SELECT TOP (1) [t0].[Key], [t0].[PackageId], [t0].[PackageNormalizedVersion], [t0].[Enqueued], [t0].[ValidationTrackingId], [t0].[Completed], [t0].[RowVersion]
FROM [PackageRevalidations] AS [t0]
WHERE (NOT ([t0].[Completed] = 1)) AND ([t0].[Enqueued] IS NULL) AND (NOT (EXISTS(
    SELECT NULL AS [EMPTY]
    FROM (
        SELECT COUNT(*) AS [value], [t1].[PackageId]
        FROM [PackageRevalidations] AS [t1]
        GROUP BY [t1].[PackageId]
        ) AS [t2]
    WHERE ([t2].[PackageId] = [t0].[PackageId]) AND ([t2].[value] > @p0)
    )))
ORDER BY [t0].[Key]

[loic-sharma]

This query builds a list of packages that have too many versions, and filters out PackageRevalidations that are on that list.

An alternative query would be: find all packages with less versions than MaximumPackageVersions, and use that to find the next revalidation. Such a query is much more expensive as the list of packages with less versions than MaximumPackageVersions is huge.