Removed instructions-text from interactive-graph

Summary: There have been several overlap-related issues with the instructions text.
Removing it for now, until a better solution has been implemented. Fixes T2667.

Test Plan: See [this example](http://localhost:9000/test.html#content=%7B%22question%22%3A%7B%22content%22%3A%22%5B%5B%E2%98%83%20interactive-graph%201%5D%5D%5Cntext%20that's%20not%20hidden%5Cn%5Cnmore%20text%20that's%20not%20hidden%5Cn%5Cn%5B%5B%E2%98%83%20interactive-graph%202%5D%5D%5Cn%5Cn%5B%5B%E2%98%83%20radio%201%5D%5D%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%22interactive-graph%201%22%3A%7B%22type%22%3A%22interactive-graph%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22step%22%3A%5B1%2C1%5D%2C%22backgroundImage%22%3A%7B%22url%22%3Anull%2C%22scale%22%3A1%2C%22bottom%22%3A0%2C%22left%22%3A0%7D%2C%22markings%22%3A%22graph%22%2C%22labels%22%3A%5B%22x%22%2C%22y%22%5D%2C%22showProtractor%22%3Afalse%2C%22showRuler%22%3Afalse%2C%22rulerLabel%22%3A%22%22%2C%22rulerTicks%22%3A10%2C%22range%22%3A%5B%5B-10%2C10%5D%2C%5B-10%2C10%5D%5D%2C%22gridStep%22%3A%5B1%2C1%5D%2C%22snapStep%22%3A%5B0.5%2C0.5%5D%2C%22graph%22%3A%7B%22type%22%3A%22point%22%2C%22numPoints%22%3A%22unlimited%22%7D%2C%22correct%22%3A%7B%22type%22%3A%22point%22%2C%22numPoints%22%3A%22unlimited%22%2C%22coords%22%3A%5B%5D%7D%7D%7D%2C%22interactive-graph%202%22%3A%7B%22type%22%3A%22interactive-graph%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22step%22%3A%5B1%2C1%5D%2C%22backgroundImage%22%3A%7B%22url%22%3Anull%2C%22scale%22%3A1%2C%22bottom%22%3A0%2C%22left%22%3A0%7D%2C%22markings%22%3A%22graph%22%2C%22labels%22%3A%5B%22x%22%2C%22y%22%5D%2C%22showProtractor%22%3Afalse%2C%22showRuler%22%3Afalse%2C%22rulerLabel%22%3A%22%22%2C%22rulerTicks%22%3A10%2C%22range%22%3A%5B%5B-10%2C10%5D%2C%5B-10%2C10%5D%5D%2C%22gridStep%22%3A%5B1%2C1%5D%2C%22snapStep%22%3A%5B0.5%2C0.5%5D%2C%22graph%22%3A%7B%22type%22%3A%22linear%22%7D%2C%22correct%22%3A%7B%22type%22%3A%22linear%22%2C%22coords%22%3Anull%7D%7D%7D%2C%22radio%201%22%3A%7B%22type%22%3A%22radio%22%2C%22graded%22%3Atrue%2C%22options%22%3A%7B%22choices%22%3A%5B%7B%22content%22%3A%22ABC%22%2C%22correct%22%3Atrue%7D%2C%7B%22content%22%3A%22DEF%22%2C%22correct%22%3Afalse%7D%5D%2C%22randomize%22%3Afalse%2C%22multipleSelect%22%3Atrue%2C%22displayCount%22%3Anull%2C%22onePerLine%22%3Atrue%7D%7D%7D%7D%2C%22answerArea%22%3A%7B%22type%22%3A%22multiple%22%2C%22options%22%3A%7B%22content%22%3A%22%22%2C%22images%22%3A%7B%7D%2C%22widgets%22%3A%7B%7D%7D%2C%22calculator%22%3Afalse%7D%2C%22hints%22%3A%5B%5D%7D)

Auditors: jack