(DOCSP-35172) removes link to third party throughput calculator (#28)

[JIRA](https://jira.mongodb.org/browse/DOCSP-35173)

[Staging](https://preview-mongodbcarriecwk.gatsbyjs.io/ops-manager/DOCSP-35172/core/backup-preparations/)

[Build](https://workerpool-boxgs.mongodbstitch.com/pages/job.html?collName=queue&jobId=659f0165dcc0144a510383a8)

Author: carriecwk

source/includes/fact-backup-sizing-recommendation.rst

@@ -18,8 +18,8 @@ and network bandwidth.
    - The network connection has very low packet loss and a low round
      trip delay time.
 
-   A *full* backup of your data would take *more than 30 hours to
-   complete*. [*]_
+   Under such circumstances, a *full* backup of your data could 
+   take *more than 30 hours to complete*.
 
    This doesn't account for disk read and write speeds, which can be,
    at most, 3 Gbps reads and 1 Gbps writes for a single or mirrored
@@ -33,8 +33,4 @@ and network bandwidth.
    into 4 shards, each shard runs its backup separately. This results
    in a backup that takes less than 8 hours to complete.
 
-   .. [*]
-      These throughput figures were calculated using the `Network
-      Throughput Calculator <https://wintelguy.com/wanperf.pl>`__ and
-      assume no additional network compression.
-      
+