[Fix]change gradeid to grade name and other text in the page display

[wsun4ipipeline]

There are some pages that still use Level or gradeId, which need change to grade name
include but not limited below pages:

• studentInfo
• admin activities
• header bar

more text modifications in the start test pages
`Welcome to Level ___!

In this contest, students will identify __ Chinese words.

If the student identifies the word correctly, press the green button; if incorrect, press the red button.

There are no half points. The student either gets it correct or incorrect.

Each word will be displayed for __ seconds.

If time runs out, it will be considered incorrect.`