out_azure_blob: increase buffer dir name size to avoid truncating the directory

**Is your feature request related to a problem? Please describe.**
Inside the `plugins/out_azure_blob/azure_blob.c` in the `azure_blob_store_init()` method, we set `char tmp[64];`. This is causing an issue for when the output directory names are too long, then become truncated.

**Describe the solution you'd like**
Could we make it longer to `1024` as is the case in other outputs like S3?
