feat(logging)!: increase DefaultEntryByteThreshold to 8Mb (#4247)
feat(logging)!: increase DefaultEntryByteThreshold to 8Mb (#4247)

Fixes: #3823 

DefaultEntryByteThreshold = `1 << 20 // 1MiB` ===> `1 << 23 // 8MiB` since size of an entries.write request	can be up to 10 MB. 

`DefaultBufferedByteLimit` is unchanged as that's more a cap on memory utilization. 
googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go