Remove examples if-then-else pattern

@ajkannan

In bigquery example we have the following patttern:

Table table = getTable(...);
if (table == null) {
  // create table
} else {
  // load data
}

in storage we have:

Blob blob = getBlob(...);
if (blob == null) {
  // create blob
} else {
  // get and update blob's content
}

In both cases we should remove the else branch and rather execute it after table/blob creation.

Also in datastore we do:

Entity entity = getEntity(...);
if (entity = null) {
  // create entity
} else {
  // update entity access type
}

@ajkannan @aozarov @mderka Do you guys think we should remove the else branch also for datastore's example? It makes slightly less sense to me.

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