Update filtered graph to make x-axis values dynamic

[wwelling]

• With current implementation, the x-axis range for Researchers is static with range from 0 to 3000, As displayed in following image.

• Change the x-axis range for Researchers so that it can be dynamic based on the count of the result set. (similar to Publications)

[wwelling]

https://github.com/TAMULib/scholars-angular/blob/tamu-main/src/app/%2Bdata-and-analytics/academic-age-group/barplot/barplot.component.ts