The "x/mongo/driver/uuid package currently uses "crypto/rand" as its randomness source for generating UUIDs. The cryptographically secure randomness source on some systems can be extremely slow. Also, the driver sessions specification specifically suggests using a pseudo-random number generator.

See a CockroachDB discussion on "crypto/rand" performance for more context.

Definition of done:

• "x/mongo/driver/uuid uses "math/rand" instead of "crypto/rand".
• "x/mongo/driver/uuid uses a package-specific random reader, not the global random reader.
• Seed the "math/rand" pseudo-random number generator with the current time.