Remove dead links from Firedrake 25 conference (#4566)

Author: connorjward

docs/source/firedrake_25.rst

@@ -70,7 +70,7 @@ Conference dinner
 Registration includes a drinks reception and three-course dinner at University House, University of Leeds. The dinner will take place on the evening of 16 September. 
 
 It is possible to bring non-registered companions to the dinner. To do so please purchase a ticket
-by following `this link <https://store.leeds.ac.uk/product-catalogue/faculty-of-engineering-and-physical-sciences/faculty-of-engineering/firedrake-2025-dinner>`__.
+by following this link.
 
 .. image:: images/university_house_leeds.jpg
    :width: 80%
@@ -81,9 +81,7 @@ by following `this link <https://store.leeds.ac.uk/product-catalogue/faculty-of-
 Registration
 ------------
 
-`Registration
-<https://app.onlinesurveys.jisc.ac.uk/s/leeds/firedrake-2025-registration>`__
-is now open.
+Registration is now open.
 
 In addition to registering to attend, participants need to pay for their
 registration using the links below.
@@ -93,9 +91,9 @@ The registration fees will be as follows:
 .. list-table::
    :widths: 25 25
 
-   * - `Student <https://store.leeds.ac.uk/product-catalogue/faculty-of-engineering-and-physical-sciences/faculty-of-engineering/firedrake-2025-student-fee>`__
+   * - Student
      - £25
-   * - `Non-student <https://store.leeds.ac.uk/product-catalogue/faculty-of-engineering-and-physical-sciences/faculty-of-engineering/firedrake-2025-non-student-fee>`__
+   * - Non-student
      - £115
 
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