refactor(attendees.ts): update total attendees query

[IndySeh]

Description

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• Refactored the code to use the count() function for calculating totalAttendees directly in the query.
• Removed the previous implementation that used the reduce function to calculate the total number of attendees.

Changes Made

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• Updated the query to use count(attendees.id) for counting total attendees.
• Removed the reduce function logic and replaced it with the new method of extracting totalAttendees.

const counts = await db
      .select({
        totalAttendees: count(attendees.id),
      })
      .from(events)
      .leftJoin(rsvps, eq(rsvps.eventId, events.id))
      .leftJoin(attendees, eq(attendees.id, rsvps.attendeeId))
      .where(eq(events.createdById, userId))
      .execute()

    const [firstCount] = counts
    const totalAttendees = firstCount.totalAttendees | 0

    return totalAttendees