chore: fix experimental blob operations json string values (#1299)

Author: GarrettWu

bigframes/operations/blob.py

@@ -156,8 +156,6 @@ def display(self, n: int = 3, *, content_type: str = ""):
  n (int, default 3): number of sample blob objects to display.
  content_type (str, default ""): content type of the blob. If unset, use the blob metadata of the storage. Possible values are "image", "audio" and "video".
  """
- import bigframes.bigquery as bbq
-
  # col name doesn't matter here. Rename to avoid column name conflicts
  df = bigframes.series.Series(self._block).rename("blob_col").head(n).to_frame()
 
@@ -187,11 +185,7 @@ def display_single_url(read_url: str, content_type: str):
  ipy_display.display(response.content, raw=True)
 
  for _, row in df.iterrows():
- # both are JSON-formated strings
- read_url = str(row["read_url"]).strip('"')
- content_type = str(row["content_type"]).strip('"')
-
- display_single_url(read_url, content_type)
+ display_single_url(row["read_url"], row["content_type"])
 
  def image_blur(
  self,